diff --git a/src/v1/providers/analytics.ts b/src/v1/providers/analytics.ts
index 0cc0083b9..87042bab8 100644
--- a/src/v1/providers/analytics.ts
+++ b/src/v1/providers/analytics.ts
@@ -30,6 +30,9 @@ export const provider = "google.analytics";
 /** @internal */
 export const service = "app-measurement.com";
 
+/** Handler used by {@link AnalyticsEventBuilder.onLog}. */
+export type OnLogHandler = (event: AnalyticsEvent, context: EventContext) => PromiseLike<any> | any;
+
 /**
  * Registers a function to handle analytics events.
  *
@@ -75,9 +78,7 @@ export class AnalyticsEventBuilder {
    *
    * @returns A function that you can export and deploy.
    */
-  onLog(
-    handler: (event: AnalyticsEvent, context: EventContext) => PromiseLike<any> | any
-  ): CloudFunction<AnalyticsEvent> {
+  onLog(handler: OnLogHandler): CloudFunction<AnalyticsEvent> {
     const dataConstructor = (raw: LegacyEvent) => {
       return new AnalyticsEvent(raw.data);
     };
diff --git a/src/v1/providers/auth.ts b/src/v1/providers/auth.ts
index e7100b048..cf54cf37f 100644
--- a/src/v1/providers/auth.ts
+++ b/src/v1/providers/auth.ts
@@ -55,6 +55,32 @@ export type { UserRecord, UserInfo };
 
 export { HttpsError };
 
+/** Handler used by {@link UserBuilder.onCreate}. */
+export type OnCreateHandler = (user: UserRecord, context: EventContext) => PromiseLike<any> | any;
+
+/** Handler used by {@link UserBuilder.onDelete}. */
+export type OnDeleteHandler = OnCreateHandler;
+
+/** Handler used by {@link UserBuilder.beforeCreate}. */
+export type BeforeCreateHandler = (
+  user: AuthUserRecord,
+  context: AuthEventContext
+) => MaybeAsync<BeforeCreateResponse | void>;
+
+/** Handler used by {@link UserBuilder.beforeSignIn}. */
+export type BeforeSignInHandler = (
+  user: AuthUserRecord,
+  context: AuthEventContext
+) => MaybeAsync<BeforeSignInResponse | void>;
+
+/** Handler used by {@link UserBuilder.beforeEmail}. */
+export type BeforeEmailHandler = (
+  context: AuthEventContext
+) => MaybeAsync<BeforeEmailResponse | void>;
+
+/** Handler used by {@link UserBuilder.beforeSms}. */
+export type BeforeSmsHandler = (context: AuthEventContext) => MaybeAsync<BeforeSmsResponse | void>;
+
 /** @internal */
 export const provider = "google.firebase.auth";
 /** @internal */
@@ -126,9 +152,7 @@ export class UserBuilder {
    *
    * @public
    */
-  onCreate(
-    handler: (user: UserRecord, context: EventContext) => PromiseLike<any> | any
-  ): CloudFunction<UserRecord> {
+  onCreate(handler: OnCreateHandler): CloudFunction<UserRecord> {
     return this.onOperation(handler, "user.create");
   }
 
@@ -139,9 +163,7 @@ export class UserBuilder {
    *
    * @public
    */
-  onDelete(
-    handler: (user: UserRecord, context: EventContext) => PromiseLike<any> | any
-  ): CloudFunction<UserRecord> {
+  onDelete(handler: OnDeleteHandler): CloudFunction<UserRecord> {
     return this.onOperation(handler, "user.delete");
   }
 
@@ -152,12 +174,7 @@ export class UserBuilder {
    *
    * @public
    */
-  beforeCreate(
-    handler: (
-      user: AuthUserRecord,
-      context: AuthEventContext
-    ) => MaybeAsync<BeforeCreateResponse | void>
-  ): BlockingFunction {
+  beforeCreate(handler: BeforeCreateHandler): BlockingFunction {
     return this.beforeOperation(handler, "beforeCreate");
   }
 
@@ -168,24 +185,15 @@ export class UserBuilder {
    *
    * @public
    */
-  beforeSignIn(
-    handler: (
-      user: AuthUserRecord,
-      context: AuthEventContext
-    ) => MaybeAsync<BeforeSignInResponse | void>
-  ): BlockingFunction {
+  beforeSignIn(handler: BeforeSignInHandler): BlockingFunction {
     return this.beforeOperation(handler, "beforeSignIn");
   }
 
-  beforeEmail(
-    handler: (context: AuthEventContext) => MaybeAsync<BeforeEmailResponse | void>
-  ): BlockingFunction {
+  beforeEmail(handler: BeforeEmailHandler): BlockingFunction {
     return this.beforeOperation(handler, "beforeSendEmail");
   }
 
-  beforeSms(
-    handler: (context: AuthEventContext) => MaybeAsync<BeforeSmsResponse | void>
-  ): BlockingFunction {
+  beforeSms(handler: BeforeSmsHandler): BlockingFunction {
     return this.beforeOperation(handler, "beforeSendSms");
   }
 
diff --git a/src/v1/providers/database.ts b/src/v1/providers/database.ts
index baa4afcb9..007afe641 100644
--- a/src/v1/providers/database.ts
+++ b/src/v1/providers/database.ts
@@ -34,6 +34,24 @@ import { expr } from "../../params";
 
 export { DataSnapshot };
 
+/** Handler used by {@link RefBuilder.onWrite}. */
+export type OnWriteHandler<Ref extends string = string> = (
+  change: Change<DataSnapshot>,
+  context: EventContext<ParamsOf<Ref>>
+) => PromiseLike<any> | any;
+
+/** Handler used by {@link RefBuilder.onUpdate}. */
+export type OnUpdateHandler<Ref extends string = string> = OnWriteHandler<Ref>;
+
+/** Handler used by {@link RefBuilder.onCreate}. */
+export type OnCreateHandler<Ref extends string = string> = (
+  snapshot: DataSnapshot,
+  context: EventContext<ParamsOf<Ref>>
+) => PromiseLike<any> | any;
+
+/** Handler used by {@link RefBuilder.onDelete}. */
+export type OnDeleteHandler<Ref extends string = string> = OnCreateHandler<Ref>;
+
 /** @internal */
 export const provider = "google.firebase.database";
 /** @internal */
@@ -182,12 +200,7 @@ export class RefBuilder<Ref extends string> {
    *   write occurs.
    * @returns A function that you can export and deploy.
    */
-  onWrite(
-    handler: (
-      change: Change<DataSnapshot>,
-      context: EventContext<ParamsOf<Ref>>
-    ) => PromiseLike<any> | any
-  ): CloudFunction<Change<DataSnapshot>> {
+  onWrite(handler: OnWriteHandler<Ref>): CloudFunction<Change<DataSnapshot>> {
     return this.onOperation(handler, "ref.write", this.changeConstructor);
   }
 
@@ -199,12 +212,7 @@ export class RefBuilder<Ref extends string> {
    *   write occurs.
    * @returns A function which you can export and deploy.
    */
-  onUpdate(
-    handler: (
-      change: Change<DataSnapshot>,
-      context: EventContext<ParamsOf<Ref>>
-    ) => PromiseLike<any> | any
-  ): CloudFunction<Change<DataSnapshot>> {
+  onUpdate(handler: OnUpdateHandler<Ref>): CloudFunction<Change<DataSnapshot>> {
     return this.onOperation(handler, "ref.update", this.changeConstructor);
   }
 
@@ -216,12 +224,7 @@ export class RefBuilder<Ref extends string> {
    *   Firebase Realtime Database.
    * @returns A function that you can export and deploy.
    */
-  onCreate(
-    handler: (
-      snapshot: DataSnapshot,
-      context: EventContext<ParamsOf<Ref>>
-    ) => PromiseLike<any> | any
-  ): CloudFunction<DataSnapshot> {
+  onCreate(handler: OnCreateHandler<Ref>): CloudFunction<DataSnapshot> {
     const dataConstructor = (raw: LegacyEvent) => {
       const [dbInstance, path] = extractInstanceAndPath(
         raw.context.resource.name,
@@ -240,12 +243,7 @@ export class RefBuilder<Ref extends string> {
    *   Firebase Realtime Database.
    * @returns A function that you can export and deploy.
    */
-  onDelete(
-    handler: (
-      snapshot: DataSnapshot,
-      context: EventContext<ParamsOf<Ref>>
-    ) => PromiseLike<any> | any
-  ): CloudFunction<DataSnapshot> {
+  onDelete(handler: OnDeleteHandler<Ref>): CloudFunction<DataSnapshot> {
     const dataConstructor = (raw: LegacyEvent) => {
       const [dbInstance, path] = extractInstanceAndPath(
         raw.context.resource.name,
diff --git a/src/v1/providers/firestore.ts b/src/v1/providers/firestore.ts
index 1d891df09..52153427d 100644
--- a/src/v1/providers/firestore.ts
+++ b/src/v1/providers/firestore.ts
@@ -44,6 +44,27 @@ export const defaultDatabase = "(default)";
 export type DocumentSnapshot = firestore.DocumentSnapshot;
 export type QueryDocumentSnapshot = firestore.QueryDocumentSnapshot;
 
+/** Handler used by {@link DocumentBuilder.onWrite}. */
+export type OnWriteHandler<Path extends string = string> = (
+  change: Change<DocumentSnapshot>,
+  context: EventContext<ParamsOf<Path>>
+) => PromiseLike<any> | any;
+
+/** Handler used by {@link DocumentBuilder.onUpdate}. */
+export type OnUpdateHandler<Path extends string = string> = (
+  change: Change<QueryDocumentSnapshot>,
+  context: EventContext<ParamsOf<Path>>
+) => PromiseLike<any> | any;
+
+/** Handler used by {@link DocumentBuilder.onCreate}. */
+export type OnCreateHandler<Path extends string = string> = (
+  snapshot: QueryDocumentSnapshot,
+  context: EventContext<ParamsOf<Path>>
+) => PromiseLike<any> | any;
+
+/** Handler used by {@link DocumentBuilder.onDelete}. */
+export type OnDeleteHandler<Path extends string = string> = OnCreateHandler<Path>;
+
 /**
  * Select the Firestore document to listen to for events.
  * @param path Full database path to listen to. This includes the name of
@@ -166,42 +187,22 @@ export class DocumentBuilder<Path extends string> {
   }
 
   /** Respond to all document writes (creates, updates, or deletes). */
-  onWrite(
-    handler: (
-      change: Change<DocumentSnapshot>,
-      context: EventContext<ParamsOf<Path>>
-    ) => PromiseLike<any> | any
-  ): CloudFunction<Change<DocumentSnapshot>> {
+  onWrite(handler: OnWriteHandler<Path>): CloudFunction<Change<DocumentSnapshot>> {
     return this.onOperation(handler, "document.write", changeConstructor);
   }
 
   /** Respond only to document updates. */
-  onUpdate(
-    handler: (
-      change: Change<QueryDocumentSnapshot>,
-      context: EventContext<ParamsOf<Path>>
-    ) => PromiseLike<any> | any
-  ): CloudFunction<Change<QueryDocumentSnapshot>> {
+  onUpdate(handler: OnUpdateHandler<Path>): CloudFunction<Change<QueryDocumentSnapshot>> {
     return this.onOperation(handler, "document.update", changeConstructor);
   }
 
   /** Respond only to document creations. */
-  onCreate(
-    handler: (
-      snapshot: QueryDocumentSnapshot,
-      context: EventContext<ParamsOf<Path>>
-    ) => PromiseLike<any> | any
-  ): CloudFunction<QueryDocumentSnapshot> {
+  onCreate(handler: OnCreateHandler<Path>): CloudFunction<QueryDocumentSnapshot> {
     return this.onOperation(handler, "document.create", snapshotConstructor);
   }
 
   /** Respond only to document deletions. */
-  onDelete(
-    handler: (
-      snapshot: QueryDocumentSnapshot,
-      context: EventContext<ParamsOf<Path>>
-    ) => PromiseLike<any> | any
-  ): CloudFunction<QueryDocumentSnapshot> {
+  onDelete(handler: OnDeleteHandler<Path>): CloudFunction<QueryDocumentSnapshot> {
     return this.onOperation(handler, "document.delete", beforeSnapshotConstructor);
   }
 
diff --git a/src/v1/providers/https.ts b/src/v1/providers/https.ts
index 739c9e001..9dc7ba2b6 100644
--- a/src/v1/providers/https.ts
+++ b/src/v1/providers/https.ts
@@ -20,7 +20,7 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
-import * as express from "express";
+import type * as express from "express";
 
 import { convertIfPresent, convertInvoker } from "../../common/encoding";
 import {
@@ -40,14 +40,18 @@ import { wrapTraceContext } from "../../v2/trace";
 export { HttpsError };
 export type { Request, CallableContext, FunctionsErrorCode };
 
+/** Handler used by {@link onRequest}. */
+export type OnRequestHandler = (req: Request, resp: express.Response) => void | Promise<void>;
+
+/** Handler used by {@link onCall}. */
+export type OnCallHandler = (data: any, context: CallableContext) => any | Promise<any>;
+
 /**
  * Handle HTTP requests.
  * @param handler A function that takes a request and response object,
  * same signature as an Express app.
  */
-export function onRequest(
-  handler: (req: Request, resp: express.Response) => void | Promise<void>
-): HttpsFunction {
+export function onRequest(handler: OnRequestHandler): HttpsFunction {
   return _onRequestWithOptions(handler, {});
 }
 
@@ -55,15 +59,13 @@ export function onRequest(
  * Declares a callable method for clients to call using a Firebase SDK.
  * @param handler A method that takes a data and context and returns a value.
  */
-export function onCall(
-  handler: (data: any, context: CallableContext) => any | Promise<any>
-): HttpsFunction & Runnable<any> {
+export function onCall(handler: OnCallHandler): HttpsFunction & Runnable<any> {
   return _onCallWithOptions(handler, {});
 }
 
 /** @internal */
 export function _onRequestWithOptions(
-  handler: (req: Request, resp: express.Response) => void | Promise<void>,
+  handler: OnRequestHandler,
   options: DeploymentOptions
 ): HttpsFunction {
   // lets us add __endpoint without altering handler:
@@ -101,7 +103,7 @@ export function _onRequestWithOptions(
 
 /** @internal */
 export function _onCallWithOptions(
-  handler: (data: any, context: CallableContext) => any | Promise<any>,
+  handler: OnCallHandler,
   options: DeploymentOptions
 ): HttpsFunction & Runnable<any> {
   // fix the length of handler to make the call to handler consistent
diff --git a/src/v1/providers/pubsub.ts b/src/v1/providers/pubsub.ts
index 21946dea5..f604d5e78 100644
--- a/src/v1/providers/pubsub.ts
+++ b/src/v1/providers/pubsub.ts
@@ -30,6 +30,12 @@ export const provider = "google.pubsub";
 /** @internal */
 export const service = "pubsub.googleapis.com";
 
+/** Handler used by {@link TopicBuilder.onPublish}. */
+export type OnPublishHandler = (message: Message, context: EventContext) => PromiseLike<any> | any;
+
+/** Handler used by {@link ScheduleBuilder.onRun}. */
+export type OnRunHandler = (context: EventContext) => PromiseLike<any> | any;
+
 /**
  * Registers a Cloud Function triggered when a Google Cloud Pub/Sub message
  * is sent to a specified topic.
@@ -79,9 +85,7 @@ export class TopicBuilder {
    *   is published.
    * @returns A function that you can export and deploy.
    */
-  onPublish(
-    handler: (message: Message, context: EventContext) => PromiseLike<any> | any
-  ): CloudFunction<Message> {
+  onPublish(handler: OnPublishHandler): CloudFunction<Message> {
     return makeCloudFunction({
       handler,
       provider,
@@ -156,7 +160,7 @@ export class ScheduleBuilder {
    *   scheduler job sends a Pub/Sub message.
    * @returns A function that you can export and deploy.
    */
-  onRun(handler: (context: EventContext) => PromiseLike<any> | any) {
+  onRun(handler: OnRunHandler) {
     const cloudFunction = makeCloudFunction({
       contextOnlyHandler: handler,
       provider,
diff --git a/src/v1/providers/remoteConfig.ts b/src/v1/providers/remoteConfig.ts
index cf67383dc..4ea94cf2b 100644
--- a/src/v1/providers/remoteConfig.ts
+++ b/src/v1/providers/remoteConfig.ts
@@ -28,6 +28,12 @@ export const provider = "google.firebase.remoteconfig";
 /** @internal */
 export const service = "firebaseremoteconfig.googleapis.com";
 
+/** Handler used by {@link onUpdate}. */
+export type OnUpdateHandler = (
+  version: TemplateVersion,
+  context: EventContext
+) => PromiseLike<any> | any;
+
 /**
  * Registers a function that triggers on Firebase Remote Config template
  * update events.
@@ -37,15 +43,13 @@ export const service = "firebaseremoteconfig.googleapis.com";
  *
  * @returns A function that you can export and deploy.
  */
-export function onUpdate(
-  handler: (version: TemplateVersion, context: EventContext) => PromiseLike<any> | any
-): CloudFunction<TemplateVersion> {
+export function onUpdate(handler: OnUpdateHandler): CloudFunction<TemplateVersion> {
   return _onUpdateWithOptions(handler, {});
 }
 
 /** @internal */
 export function _onUpdateWithOptions(
-  handler: (version: TemplateVersion, context: EventContext) => PromiseLike<any> | any,
+  handler: OnUpdateHandler,
   options: DeploymentOptions
 ): CloudFunction<TemplateVersion> {
   const triggerResource = () => {
@@ -68,9 +72,7 @@ export class UpdateBuilder {
    * @param handler A function that takes the updated Remote Config template
    * version metadata as an argument.
    */
-  onUpdate(
-    handler: (version: TemplateVersion, context: EventContext) => PromiseLike<any> | any
-  ): CloudFunction<TemplateVersion> {
+  onUpdate(handler: OnUpdateHandler): CloudFunction<TemplateVersion> {
     return makeCloudFunction({
       handler,
       provider,
diff --git a/src/v1/providers/storage.ts b/src/v1/providers/storage.ts
index a720f62fe..368054697 100644
--- a/src/v1/providers/storage.ts
+++ b/src/v1/providers/storage.ts
@@ -31,6 +31,21 @@ export const provider = "google.storage";
 /** @internal */
 export const service = "storage.googleapis.com";
 
+/** Handler used by {@link ObjectBuilder.onArchive}. */
+export type OnArchiveHandler = (
+  object: ObjectMetadata,
+  context: EventContext
+) => PromiseLike<any> | any;
+
+/** Handler used by {@link ObjectBuilder.onDelete}. */
+export type OnDeleteHandler = OnArchiveHandler;
+
+/** Handler used by {@link ObjectBuilder.onFinalize}. */
+export type OnFinalizeHandler = OnArchiveHandler;
+
+/** Handler used by {@link ObjectBuilder.onMetadataUpdate}. */
+export type OnMetadataUpdateHandler = OnArchiveHandler;
+
 /**
  * Registers a Cloud Function scoped to a specific storage bucket.
  *
@@ -125,9 +140,7 @@ export class ObjectBuilder {
    *
    * @returns A function which you can export and deploy.
    */
-  onArchive(
-    handler: (object: ObjectMetadata, context: EventContext) => PromiseLike<any> | any
-  ): CloudFunction<ObjectMetadata> {
+  onArchive(handler: OnArchiveHandler): CloudFunction<ObjectMetadata> {
     return this.onOperation(handler, "object.archive");
   }
 
@@ -145,9 +158,7 @@ export class ObjectBuilder {
    *
    * @returns A function which you can export and deploy.
    */
-  onDelete(
-    handler: (object: ObjectMetadata, context: EventContext) => PromiseLike<any> | any
-  ): CloudFunction<ObjectMetadata> {
+  onDelete(handler: OnDeleteHandler): CloudFunction<ObjectMetadata> {
     return this.onOperation(handler, "object.delete");
   }
 
@@ -164,9 +175,7 @@ export class ObjectBuilder {
    *
    * @returns A function which you can export and deploy.
    */
-  onFinalize(
-    handler: (object: ObjectMetadata, context: EventContext) => PromiseLike<any> | any
-  ): CloudFunction<ObjectMetadata> {
+  onFinalize(handler: OnFinalizeHandler): CloudFunction<ObjectMetadata> {
     return this.onOperation(handler, "object.finalize");
   }
 
@@ -179,9 +188,7 @@ export class ObjectBuilder {
    *
    * @returns A function which you can export and deploy.
    */
-  onMetadataUpdate(
-    handler: (object: ObjectMetadata, context: EventContext) => PromiseLike<any> | any
-  ): CloudFunction<ObjectMetadata> {
+  onMetadataUpdate(handler: OnMetadataUpdateHandler): CloudFunction<ObjectMetadata> {
     return this.onOperation(handler, "object.metadataUpdate");
   }
 
diff --git a/src/v1/providers/tasks.ts b/src/v1/providers/tasks.ts
index 0be9176ab..32c025bda 100644
--- a/src/v1/providers/tasks.ts
+++ b/src/v1/providers/tasks.ts
@@ -41,6 +41,9 @@ import { DeploymentOptions } from "../function-configuration";
 
 export type { RetryConfig, RateLimits, TaskContext };
 
+/** Handler used by {@link TaskQueueBuilder.onDispatch}. */
+export type OnDispatchHandler = (data: any, context: TaskContext) => void | Promise<void>;
+
 /**
  * Options for configuring the task queue to listen to.
  */
@@ -100,9 +103,7 @@ export class TaskQueueBuilder {
    * @param handler - A callback to handle task requests.
    * @returns A function you can export and deploy.
    */
-  onDispatch(
-    handler: (data: any, context: TaskContext) => void | Promise<void>
-  ): TaskQueueFunction {
+  onDispatch(handler: OnDispatchHandler): TaskQueueFunction {
     // onEnqueueHandler sniffs the function length of the passed-in callback
     // and the user could have only tried to listen to data. Wrap their handler
     // in another handler to avoid accidentally triggering the v2 API
diff --git a/src/v1/providers/testLab.ts b/src/v1/providers/testLab.ts
index 3ae851437..027b4ae20 100644
--- a/src/v1/providers/testLab.ts
+++ b/src/v1/providers/testLab.ts
@@ -30,6 +30,12 @@ export const SERVICE = "testing.googleapis.com";
 /** @internal */
 export const TEST_MATRIX_COMPLETE_EVENT_TYPE = "testMatrix.complete";
 
+/** Handler used by {@link TestMatrixBuilder.onComplete}. */
+export type OnCompleteHandler = (
+  testMatrix: TestMatrix,
+  context: EventContext
+) => PromiseLike<any> | any;
+
 /** Handle events related to Test Lab test matrices. */
 export function testMatrix() {
   return _testMatrixWithOpts({});
@@ -51,9 +57,7 @@ export class TestMatrixBuilder {
   constructor(private triggerResource: () => string, private options: DeploymentOptions) {}
 
   /** Handle a TestMatrix that reached a final test state. */
-  onComplete(
-    handler: (testMatrix: TestMatrix, context: EventContext) => PromiseLike<any> | any
-  ): CloudFunction<TestMatrix> {
+  onComplete(handler: OnCompleteHandler): CloudFunction<TestMatrix> {
     const dataConstructor = (raw: LegacyEvent) => {
       return new TestMatrix(raw.data);
     };
diff --git a/src/v2/providers/ai/index.ts b/src/v2/providers/ai/index.ts
index 413beb685..e5068c994 100644
--- a/src/v2/providers/ai/index.ts
+++ b/src/v2/providers/ai/index.ts
@@ -151,33 +151,29 @@ type MaybeAsync<T> = T | Promise<T>;
 
 export type BlockingFunction = HttpsFunction;
 
-export function beforeGenerateContent(
-  callback: (
-    event: AIBlockingEvent<BeforeGenerateContentData>
-  ) => MaybeAsync<void | Partial<AnyValidAIRequest>>
-): BlockingFunction;
+/** Handler used by {@link beforeGenerateContent}. */
+export type BeforeGenerateContentHandler = (
+  event: AIBlockingEvent<BeforeGenerateContentData>
+) => MaybeAsync<void | Partial<AnyValidAIRequest>>;
+
+/** Handler used by {@link afterGenerateContent}. */
+export type AfterGenerateContentHandler = (
+  event: AIBlockingEvent<AfterGenerateContentData>
+) => MaybeAsync<void | Partial<AnyValidAIResponse>>;
+
+export function beforeGenerateContent(callback: BeforeGenerateContentHandler): BlockingFunction;
 
 export function beforeGenerateContent<Regional extends boolean = false>(
   options: WebhookOptions<Regional>,
-  callback: (
-    event: AIBlockingEvent<BeforeGenerateContentData>
-  ) => MaybeAsync<void | Partial<AnyValidAIRequest>>
+  callback: BeforeGenerateContentHandler
 ): BlockingFunction;
 
 export function beforeGenerateContent(
-  optsOrCb:
-    | WebhookOptions
-    | ((
-        event: AIBlockingEvent<BeforeGenerateContentData>
-      ) => MaybeAsync<void | Partial<AnyValidAIRequest>>),
-  cb?: (
-    event: AIBlockingEvent<BeforeGenerateContentData>
-  ) => MaybeAsync<void | Partial<AnyValidAIRequest>>
+  optsOrCb: WebhookOptions | BeforeGenerateContentHandler,
+  cb?: BeforeGenerateContentHandler
 ): BlockingFunction {
   let opts: WebhookOptions;
-  let handler: (
-    event: AIBlockingEvent<BeforeGenerateContentData>
-  ) => MaybeAsync<void | Partial<AnyValidAIRequest>>;
+  let handler: BeforeGenerateContentHandler;
 
   if (arguments.length === 1) {
     opts = {};
@@ -258,33 +254,19 @@ export function beforeGenerateContent(
   return func as BlockingFunction;
 }
 
-export function afterGenerateContent(
-  callback: (
-    event: AIBlockingEvent<AfterGenerateContentData>
-  ) => MaybeAsync<void | Partial<AnyValidAIResponse>>
-): BlockingFunction;
+export function afterGenerateContent(callback: AfterGenerateContentHandler): BlockingFunction;
 
 export function afterGenerateContent<Regional extends boolean = false>(
   options: WebhookOptions<Regional>,
-  callback: (
-    event: AIBlockingEvent<AfterGenerateContentData>
-  ) => MaybeAsync<void | Partial<AnyValidAIResponse>>
+  callback: AfterGenerateContentHandler
 ): BlockingFunction;
 
 export function afterGenerateContent(
-  optsOrCb:
-    | WebhookOptions
-    | ((
-        event: AIBlockingEvent<AfterGenerateContentData>
-      ) => MaybeAsync<void | Partial<AnyValidAIResponse>>),
-  cb?: (
-    event: AIBlockingEvent<AfterGenerateContentData>
-  ) => MaybeAsync<void | Partial<AnyValidAIResponse>>
+  optsOrCb: WebhookOptions | AfterGenerateContentHandler,
+  cb?: AfterGenerateContentHandler
 ): BlockingFunction {
   let opts: WebhookOptions;
-  let handler: (
-    event: AIBlockingEvent<AfterGenerateContentData>
-  ) => MaybeAsync<void | Partial<AnyValidAIResponse>>;
+  let handler: AfterGenerateContentHandler;
 
   if (arguments.length === 1) {
     opts = {};
diff --git a/src/v2/providers/alerts/alerts.ts b/src/v2/providers/alerts/alerts.ts
index 1cfacd706..15c968ca4 100644
--- a/src/v2/providers/alerts/alerts.ts
+++ b/src/v2/providers/alerts/alerts.ts
@@ -186,6 +186,11 @@ export interface FirebaseAlertOptions extends options.EventHandlerOptions {
   retry?: boolean | Expression<boolean> | ResetValue;
 }
 
+/** Handler used by {@link onAlertPublished}. */
+export type OnAlertPublishedHandler<T extends { ["@type"]: string } = any> = (
+  event: AlertEvent<T>
+) => any | Promise<any>;
+
 /**
  * Declares a function that can handle Firebase Alerts from CloudEvents.
  * @typeParam T - the type of event.data.payload.
@@ -195,7 +200,7 @@ export interface FirebaseAlertOptions extends options.EventHandlerOptions {
  */
 export function onAlertPublished<T extends { ["@type"]: string } = any>(
   alertType: AlertType,
-  handler: (event: AlertEvent<T>) => any | Promise<any>
+  handler: OnAlertPublishedHandler<T>
 ): CloudFunction<AlertEvent<T>>;
 
 /**
@@ -206,12 +211,12 @@ export function onAlertPublished<T extends { ["@type"]: string } = any>(
  */
 export function onAlertPublished<T extends { ["@type"]: string } = any>(
   options: FirebaseAlertOptions,
-  handler: (event: AlertEvent<T>) => any | Promise<any>
+  handler: OnAlertPublishedHandler<T>
 ): CloudFunction<AlertEvent<T>>;
 
 export function onAlertPublished<T extends { ["@type"]: string } = any>(
   alertTypeOrOpts: AlertType | FirebaseAlertOptions,
-  handler: (event: AlertEvent<T>) => any | Promise<any>
+  handler: OnAlertPublishedHandler<T>
 ): CloudFunction<AlertEvent<T>> {
   const [opts, alertType, appId] = getOptsAndAlertTypeAndApp(alertTypeOrOpts);
 
diff --git a/src/v2/providers/alerts/appDistribution.ts b/src/v2/providers/alerts/appDistribution.ts
index a26c5e108..fca01ae75 100644
--- a/src/v2/providers/alerts/appDistribution.ts
+++ b/src/v2/providers/alerts/appDistribution.ts
@@ -197,13 +197,23 @@ export interface AppDistributionOptions extends options.EventHandlerOptions {
   retry?: boolean | Expression<boolean> | ResetValue;
 }
 
+/** Handler used by {@link onNewTesterIosDevicePublished}. */
+export type OnNewTesterIosDevicePublishedHandler = (
+  event: AppDistributionEvent<NewTesterDevicePayload>
+) => any | Promise<any>;
+
+/** Handler used by {@link onInAppFeedbackPublished}. */
+export type OnInAppFeedbackPublishedHandler = (
+  event: AppDistributionEvent<InAppFeedbackPayload>
+) => any | Promise<any>;
+
 /**
  * Declares a function that can handle adding a new tester iOS device.
  * @param handler - Event handler which is run every time a new tester iOS device is added.
  * @returns A function that you can export and deploy.
  */
 export function onNewTesterIosDevicePublished(
-  handler: (event: AppDistributionEvent<NewTesterDevicePayload>) => any | Promise<any>
+  handler: OnNewTesterIosDevicePublishedHandler
 ): CloudFunction<AppDistributionEvent<NewTesterDevicePayload>>;
 
 /**
@@ -214,7 +224,7 @@ export function onNewTesterIosDevicePublished(
  */
 export function onNewTesterIosDevicePublished(
   appId: string,
-  handler: (event: AppDistributionEvent<NewTesterDevicePayload>) => any | Promise<any>
+  handler: OnNewTesterIosDevicePublishedHandler
 ): CloudFunction<AppDistributionEvent<NewTesterDevicePayload>>;
 
 /**
@@ -225,7 +235,7 @@ export function onNewTesterIosDevicePublished(
  */
 export function onNewTesterIosDevicePublished(
   opts: AppDistributionOptions,
-  handler: (event: AppDistributionEvent<NewTesterDevicePayload>) => any | Promise<any>
+  handler: OnNewTesterIosDevicePublishedHandler
 ): CloudFunction<AppDistributionEvent<NewTesterDevicePayload>>;
 
 /**
@@ -235,11 +245,8 @@ export function onNewTesterIosDevicePublished(
  * @returns A function that you can export and deploy.
  */
 export function onNewTesterIosDevicePublished(
-  appIdOrOptsOrHandler:
-    | string
-    | AppDistributionOptions
-    | ((event: AppDistributionEvent<NewTesterDevicePayload>) => any | Promise<any>),
-  handler?: (event: AppDistributionEvent<NewTesterDevicePayload>) => any | Promise<any>
+  appIdOrOptsOrHandler: string | AppDistributionOptions | OnNewTesterIosDevicePublishedHandler,
+  handler?: OnNewTesterIosDevicePublishedHandler
 ): CloudFunction<AppDistributionEvent<NewTesterDevicePayload>> {
   if (typeof appIdOrOptsOrHandler === "function") {
     handler = appIdOrOptsOrHandler as (
@@ -268,7 +275,7 @@ export function onNewTesterIosDevicePublished(
  * @returns A function that you can export and deploy.
  */
 export function onInAppFeedbackPublished(
-  handler: (event: AppDistributionEvent<InAppFeedbackPayload>) => any | Promise<any>
+  handler: OnInAppFeedbackPublishedHandler
 ): CloudFunction<AppDistributionEvent<InAppFeedbackPayload>>;
 
 /**
@@ -279,7 +286,7 @@ export function onInAppFeedbackPublished(
  */
 export function onInAppFeedbackPublished(
   appId: string,
-  handler: (event: AppDistributionEvent<InAppFeedbackPayload>) => any | Promise<any>
+  handler: OnInAppFeedbackPublishedHandler
 ): CloudFunction<AppDistributionEvent<InAppFeedbackPayload>>;
 
 /**
@@ -290,7 +297,7 @@ export function onInAppFeedbackPublished(
  */
 export function onInAppFeedbackPublished(
   opts: AppDistributionOptions,
-  handler: (event: AppDistributionEvent<InAppFeedbackPayload>) => any | Promise<any>
+  handler: OnInAppFeedbackPublishedHandler
 ): CloudFunction<AppDistributionEvent<InAppFeedbackPayload>>;
 
 /**
@@ -300,11 +307,8 @@ export function onInAppFeedbackPublished(
  * @returns A function that you can export and deploy.
  */
 export function onInAppFeedbackPublished(
-  appIdOrOptsOrHandler:
-    | string
-    | AppDistributionOptions
-    | ((event: AppDistributionEvent<InAppFeedbackPayload>) => any | Promise<any>),
-  handler?: (event: AppDistributionEvent<InAppFeedbackPayload>) => any | Promise<any>
+  appIdOrOptsOrHandler: string | AppDistributionOptions | OnInAppFeedbackPublishedHandler,
+  handler?: OnInAppFeedbackPublishedHandler
 ): CloudFunction<AppDistributionEvent<InAppFeedbackPayload>> {
   if (typeof appIdOrOptsOrHandler === "function") {
     handler = appIdOrOptsOrHandler as (
diff --git a/src/v2/providers/alerts/billing.ts b/src/v2/providers/alerts/billing.ts
index 8bdb10d3d..a09df2219 100644
--- a/src/v2/providers/alerts/billing.ts
+++ b/src/v2/providers/alerts/billing.ts
@@ -71,13 +71,26 @@ export const planUpdateAlert = "billing.planUpdate";
 /** @internal */
 export const planAutomatedUpdateAlert = "billing.planAutomatedUpdate";
 
+/** Handler used by {@link onPlanUpdatePublished}. */
+export type OnPlanUpdatePublishedHandler = (
+  event: BillingEvent<PlanUpdatePayload>
+) => any | Promise<any>;
+
+/** Handler used by {@link onPlanAutomatedUpdatePublished}. */
+export type OnPlanAutomatedUpdatePublishedHandler = (
+  event: BillingEvent<PlanAutomatedUpdatePayload>
+) => any | Promise<any>;
+
+/** Handler used by internal billing alert operations. */
+export type OnBillingOperationHandler<T> = (event: BillingEvent<T>) => any | Promise<any>;
+
 /**
  * Declares a function that can handle a billing plan update event.
  * @param handler - Event handler which is run every time a billing plan is updated.
  * @returns A function that you can export and deploy.
  */
 export function onPlanUpdatePublished(
-  handler: (event: BillingEvent<PlanUpdatePayload>) => any | Promise<any>
+  handler: OnPlanUpdatePublishedHandler
 ): CloudFunction<BillingEvent<PlanUpdatePayload>>;
 
 /**
@@ -88,7 +101,7 @@ export function onPlanUpdatePublished(
  */
 export function onPlanUpdatePublished(
   opts: options.EventHandlerOptions,
-  handler: (event: BillingEvent<PlanUpdatePayload>) => any | Promise<any>
+  handler: OnPlanUpdatePublishedHandler
 ): CloudFunction<BillingEvent<PlanUpdatePayload>>;
 
 /**
@@ -98,10 +111,8 @@ export function onPlanUpdatePublished(
  * @returns A function that you can export and deploy.
  */
 export function onPlanUpdatePublished(
-  optsOrHandler:
-    | options.EventHandlerOptions
-    | ((event: BillingEvent<PlanUpdatePayload>) => any | Promise<any>),
-  handler?: (event: BillingEvent<PlanUpdatePayload>) => any | Promise<any>
+  optsOrHandler: options.EventHandlerOptions | OnPlanUpdatePublishedHandler,
+  handler?: OnPlanUpdatePublishedHandler
 ): CloudFunction<BillingEvent<PlanUpdatePayload>> {
   return onOperation<PlanUpdatePayload>(planUpdateAlert, optsOrHandler, handler);
 }
@@ -112,7 +123,7 @@ export function onPlanUpdatePublished(
  * @returns A function that you can export and deploy.
  */
 export function onPlanAutomatedUpdatePublished(
-  handler: (event: BillingEvent<PlanAutomatedUpdatePayload>) => any | Promise<any>
+  handler: OnPlanAutomatedUpdatePublishedHandler
 ): CloudFunction<BillingEvent<PlanAutomatedUpdatePayload>>;
 
 /**
@@ -123,7 +134,7 @@ export function onPlanAutomatedUpdatePublished(
  */
 export function onPlanAutomatedUpdatePublished(
   opts: options.EventHandlerOptions,
-  handler: (event: BillingEvent<PlanAutomatedUpdatePayload>) => any | Promise<any>
+  handler: OnPlanAutomatedUpdatePublishedHandler
 ): CloudFunction<BillingEvent<PlanAutomatedUpdatePayload>>;
 
 /**
@@ -133,10 +144,8 @@ export function onPlanAutomatedUpdatePublished(
  * @returns A function that you can export and deploy.
  */
 export function onPlanAutomatedUpdatePublished(
-  optsOrHandler:
-    | options.EventHandlerOptions
-    | ((event: BillingEvent<PlanAutomatedUpdatePayload>) => any | Promise<any>),
-  handler?: (event: BillingEvent<PlanAutomatedUpdatePayload>) => any | Promise<any>
+  optsOrHandler: options.EventHandlerOptions | OnPlanAutomatedUpdatePublishedHandler,
+  handler?: OnPlanAutomatedUpdatePublishedHandler
 ): CloudFunction<BillingEvent<PlanAutomatedUpdatePayload>> {
   return onOperation<PlanAutomatedUpdatePayload>(planAutomatedUpdateAlert, optsOrHandler, handler);
 }
@@ -144,11 +153,11 @@ export function onPlanAutomatedUpdatePublished(
 /** @internal */
 export function onOperation<T>(
   alertType: string,
-  optsOrHandler: options.EventHandlerOptions | ((event: BillingEvent<T>) => any | Promise<any>),
-  handler: (event: BillingEvent<T>) => any | Promise<any>
+  optsOrHandler: options.EventHandlerOptions | OnBillingOperationHandler<T>,
+  handler: OnBillingOperationHandler<T>
 ): CloudFunction<BillingEvent<T>> {
   if (typeof optsOrHandler === "function") {
-    handler = optsOrHandler as (event: BillingEvent<T>) => any | Promise<any>;
+    handler = optsOrHandler as OnBillingOperationHandler<T>;
     optsOrHandler = {};
   }
 
diff --git a/src/v2/providers/alerts/crashlytics.ts b/src/v2/providers/alerts/crashlytics.ts
index 638b7f18e..aee791f6d 100644
--- a/src/v2/providers/alerts/crashlytics.ts
+++ b/src/v2/providers/alerts/crashlytics.ts
@@ -277,13 +277,46 @@ export interface CrashlyticsOptions extends options.EventHandlerOptions {
   retry?: boolean | Expression<boolean> | ResetValue;
 }
 
+/** Handler used by {@link onNewFatalIssuePublished}. */
+export type OnNewFatalIssuePublishedHandler = (
+  event: CrashlyticsEvent<NewFatalIssuePayload>
+) => any | Promise<any>;
+
+/** Handler used by {@link onNewNonfatalIssuePublished}. */
+export type OnNewNonfatalIssuePublishedHandler = (
+  event: CrashlyticsEvent<NewNonfatalIssuePayload>
+) => any | Promise<any>;
+
+/** Handler used by {@link onRegressionAlertPublished}. */
+export type OnRegressionAlertPublishedHandler = (
+  event: CrashlyticsEvent<RegressionAlertPayload>
+) => any | Promise<any>;
+
+/** Handler used by {@link onStabilityDigestPublished}. */
+export type OnStabilityDigestPublishedHandler = (
+  event: CrashlyticsEvent<StabilityDigestPayload>
+) => any | Promise<any>;
+
+/** Handler used by {@link onVelocityAlertPublished}. */
+export type OnVelocityAlertPublishedHandler = (
+  event: CrashlyticsEvent<VelocityAlertPayload>
+) => any | Promise<any>;
+
+/** Handler used by {@link onNewAnrIssuePublished}. */
+export type OnNewAnrIssuePublishedHandler = (
+  event: CrashlyticsEvent<NewAnrIssuePayload>
+) => any | Promise<any>;
+
+/** Handler used by internal Crashlytics alert operations. */
+export type OnCrashlyticsOperationHandler<T> = (event: CrashlyticsEvent<T>) => any | Promise<any>;
+
 /**
  * Declares a function that can handle a new fatal issue published to Crashlytics.
  * @param handler - Event handler that is triggered when a new fatal issue is published to Crashlytics.
  * @returns A function that you can export and deploy.
  */
 export function onNewFatalIssuePublished(
-  handler: (event: CrashlyticsEvent<NewFatalIssuePayload>) => any | Promise<any>
+  handler: OnNewFatalIssuePublishedHandler
 ): CloudFunction<CrashlyticsEvent<NewFatalIssuePayload>>;
 
 /**
@@ -294,7 +327,7 @@ export function onNewFatalIssuePublished(
  */
 export function onNewFatalIssuePublished(
   appId: string,
-  handler: (event: CrashlyticsEvent<NewFatalIssuePayload>) => any | Promise<any>
+  handler: OnNewFatalIssuePublishedHandler
 ): CloudFunction<CrashlyticsEvent<NewFatalIssuePayload>>;
 
 /**
@@ -305,7 +338,7 @@ export function onNewFatalIssuePublished(
  */
 export function onNewFatalIssuePublished(
   opts: CrashlyticsOptions,
-  handler: (event: CrashlyticsEvent<NewFatalIssuePayload>) => any | Promise<any>
+  handler: OnNewFatalIssuePublishedHandler
 ): CloudFunction<CrashlyticsEvent<NewFatalIssuePayload>>;
 
 /**
@@ -315,11 +348,8 @@ export function onNewFatalIssuePublished(
  * @returns A function that you can export and deploy.
  */
 export function onNewFatalIssuePublished(
-  appIdOrOptsOrHandler:
-    | string
-    | CrashlyticsOptions
-    | ((event: CrashlyticsEvent<NewFatalIssuePayload>) => any | Promise<any>),
-  handler?: (event: CrashlyticsEvent<NewFatalIssuePayload>) => any | Promise<any>
+  appIdOrOptsOrHandler: string | CrashlyticsOptions | OnNewFatalIssuePublishedHandler,
+  handler?: OnNewFatalIssuePublishedHandler
 ): CloudFunction<CrashlyticsEvent<NewFatalIssuePayload>> {
   return onOperation<NewFatalIssuePayload>(newFatalIssueAlert, appIdOrOptsOrHandler, handler);
 }
@@ -330,7 +360,7 @@ export function onNewFatalIssuePublished(
  * @returns A function that you can export and deploy.
  */
 export function onNewNonfatalIssuePublished(
-  handler: (event: CrashlyticsEvent<NewNonfatalIssuePayload>) => any | Promise<any>
+  handler: OnNewNonfatalIssuePublishedHandler
 ): CloudFunction<CrashlyticsEvent<NewNonfatalIssuePayload>>;
 
 /**
@@ -341,7 +371,7 @@ export function onNewNonfatalIssuePublished(
  */
 export function onNewNonfatalIssuePublished(
   appId: string,
-  handler: (event: CrashlyticsEvent<NewNonfatalIssuePayload>) => any | Promise<any>
+  handler: OnNewNonfatalIssuePublishedHandler
 ): CloudFunction<CrashlyticsEvent<NewNonfatalIssuePayload>>;
 
 /**
@@ -352,7 +382,7 @@ export function onNewNonfatalIssuePublished(
  */
 export function onNewNonfatalIssuePublished(
   opts: CrashlyticsOptions,
-  handler: (event: CrashlyticsEvent<NewNonfatalIssuePayload>) => any | Promise<any>
+  handler: OnNewNonfatalIssuePublishedHandler
 ): CloudFunction<CrashlyticsEvent<NewNonfatalIssuePayload>>;
 
 /**
@@ -362,11 +392,8 @@ export function onNewNonfatalIssuePublished(
  * @returns A function that you can export and deploy.
  */
 export function onNewNonfatalIssuePublished(
-  appIdOrOptsOrHandler:
-    | string
-    | CrashlyticsOptions
-    | ((event: CrashlyticsEvent<NewNonfatalIssuePayload>) => any | Promise<any>),
-  handler?: (event: CrashlyticsEvent<NewNonfatalIssuePayload>) => any | Promise<any>
+  appIdOrOptsOrHandler: string | CrashlyticsOptions | OnNewNonfatalIssuePublishedHandler,
+  handler?: OnNewNonfatalIssuePublishedHandler
 ): CloudFunction<CrashlyticsEvent<NewNonfatalIssuePayload>> {
   return onOperation<NewNonfatalIssuePayload>(newNonfatalIssueAlert, appIdOrOptsOrHandler, handler);
 }
@@ -377,7 +404,7 @@ export function onNewNonfatalIssuePublished(
  * @returns A function that you can export and deploy.
  */
 export function onRegressionAlertPublished(
-  handler: (event: CrashlyticsEvent<RegressionAlertPayload>) => any | Promise<any>
+  handler: OnRegressionAlertPublishedHandler
 ): CloudFunction<CrashlyticsEvent<RegressionAlertPayload>>;
 
 /**
@@ -389,7 +416,7 @@ export function onRegressionAlertPublished(
  */
 export function onRegressionAlertPublished(
   appId: string,
-  handler: (event: CrashlyticsEvent<RegressionAlertPayload>) => any | Promise<any>
+  handler: OnRegressionAlertPublishedHandler
 ): CloudFunction<CrashlyticsEvent<RegressionAlertPayload>>;
 
 /**
@@ -401,7 +428,7 @@ export function onRegressionAlertPublished(
  */
 export function onRegressionAlertPublished(
   opts: CrashlyticsOptions,
-  handler: (event: CrashlyticsEvent<RegressionAlertPayload>) => any | Promise<any>
+  handler: OnRegressionAlertPublishedHandler
 ): CloudFunction<CrashlyticsEvent<RegressionAlertPayload>>;
 
 /**
@@ -411,11 +438,8 @@ export function onRegressionAlertPublished(
  * @returns A function that you can export and deploy.
  */
 export function onRegressionAlertPublished(
-  appIdOrOptsOrHandler:
-    | string
-    | CrashlyticsOptions
-    | ((event: CrashlyticsEvent<RegressionAlertPayload>) => any | Promise<any>),
-  handler?: (event: CrashlyticsEvent<RegressionAlertPayload>) => any | Promise<any>
+  appIdOrOptsOrHandler: string | CrashlyticsOptions | OnRegressionAlertPublishedHandler,
+  handler?: OnRegressionAlertPublishedHandler
 ): CloudFunction<CrashlyticsEvent<RegressionAlertPayload>> {
   return onOperation<RegressionAlertPayload>(regressionAlert, appIdOrOptsOrHandler, handler);
 }
@@ -426,7 +450,7 @@ export function onRegressionAlertPublished(
  * @returns A function that you can export and deploy.
  */
 export function onStabilityDigestPublished(
-  handler: (event: CrashlyticsEvent<StabilityDigestPayload>) => any | Promise<any>
+  handler: OnStabilityDigestPublishedHandler
 ): CloudFunction<CrashlyticsEvent<StabilityDigestPayload>>;
 
 /**
@@ -438,7 +462,7 @@ export function onStabilityDigestPublished(
  */
 export function onStabilityDigestPublished(
   appId: string,
-  handler: (event: CrashlyticsEvent<StabilityDigestPayload>) => any | Promise<any>
+  handler: OnStabilityDigestPublishedHandler
 ): CloudFunction<CrashlyticsEvent<StabilityDigestPayload>>;
 
 /**
@@ -450,7 +474,7 @@ export function onStabilityDigestPublished(
  */
 export function onStabilityDigestPublished(
   opts: CrashlyticsOptions,
-  handler: (event: CrashlyticsEvent<StabilityDigestPayload>) => any | Promise<any>
+  handler: OnStabilityDigestPublishedHandler
 ): CloudFunction<CrashlyticsEvent<StabilityDigestPayload>>;
 
 /**
@@ -460,11 +484,8 @@ export function onStabilityDigestPublished(
  * @returns A function that you can export and deploy.
  */
 export function onStabilityDigestPublished(
-  appIdOrOptsOrHandler:
-    | string
-    | CrashlyticsOptions
-    | ((event: CrashlyticsEvent<StabilityDigestPayload>) => any | Promise<any>),
-  handler?: (event: CrashlyticsEvent<StabilityDigestPayload>) => any | Promise<any>
+  appIdOrOptsOrHandler: string | CrashlyticsOptions | OnStabilityDigestPublishedHandler,
+  handler?: OnStabilityDigestPublishedHandler
 ): CloudFunction<CrashlyticsEvent<StabilityDigestPayload>> {
   return onOperation<StabilityDigestPayload>(stabilityDigestAlert, appIdOrOptsOrHandler, handler);
 }
@@ -475,7 +496,7 @@ export function onStabilityDigestPublished(
  * @returns A function that you can export and deploy.
  */
 export function onVelocityAlertPublished(
-  handler: (event: CrashlyticsEvent<VelocityAlertPayload>) => any | Promise<any>
+  handler: OnVelocityAlertPublishedHandler
 ): CloudFunction<CrashlyticsEvent<VelocityAlertPayload>>;
 
 /**
@@ -486,7 +507,7 @@ export function onVelocityAlertPublished(
  */
 export function onVelocityAlertPublished(
   appId: string,
-  handler: (event: CrashlyticsEvent<VelocityAlertPayload>) => any | Promise<any>
+  handler: OnVelocityAlertPublishedHandler
 ): CloudFunction<CrashlyticsEvent<VelocityAlertPayload>>;
 
 /**
@@ -497,7 +518,7 @@ export function onVelocityAlertPublished(
  */
 export function onVelocityAlertPublished(
   opts: CrashlyticsOptions,
-  handler: (event: CrashlyticsEvent<VelocityAlertPayload>) => any | Promise<any>
+  handler: OnVelocityAlertPublishedHandler
 ): CloudFunction<CrashlyticsEvent<VelocityAlertPayload>>;
 
 /**
@@ -507,11 +528,8 @@ export function onVelocityAlertPublished(
  * @returns A function that you can export and deploy.
  */
 export function onVelocityAlertPublished(
-  appIdOrOptsOrHandler:
-    | string
-    | CrashlyticsOptions
-    | ((event: CrashlyticsEvent<VelocityAlertPayload>) => any | Promise<any>),
-  handler?: (event: CrashlyticsEvent<VelocityAlertPayload>) => any | Promise<any>
+  appIdOrOptsOrHandler: string | CrashlyticsOptions | OnVelocityAlertPublishedHandler,
+  handler?: OnVelocityAlertPublishedHandler
 ): CloudFunction<CrashlyticsEvent<VelocityAlertPayload>> {
   return onOperation<VelocityAlertPayload>(velocityAlert, appIdOrOptsOrHandler, handler);
 }
@@ -522,7 +540,7 @@ export function onVelocityAlertPublished(
  * @returns A function that you can export and deploy.
  */
 export function onNewAnrIssuePublished(
-  handler: (event: CrashlyticsEvent<NewAnrIssuePayload>) => any | Promise<any>
+  handler: OnNewAnrIssuePublishedHandler
 ): CloudFunction<CrashlyticsEvent<NewAnrIssuePayload>>;
 
 /**
@@ -534,7 +552,7 @@ export function onNewAnrIssuePublished(
  */
 export function onNewAnrIssuePublished(
   appId: string,
-  handler: (event: CrashlyticsEvent<NewAnrIssuePayload>) => any | Promise<any>
+  handler: OnNewAnrIssuePublishedHandler
 ): CloudFunction<CrashlyticsEvent<NewAnrIssuePayload>>;
 
 /**
@@ -546,7 +564,7 @@ export function onNewAnrIssuePublished(
  */
 export function onNewAnrIssuePublished(
   opts: CrashlyticsOptions,
-  handler: (event: CrashlyticsEvent<NewAnrIssuePayload>) => any | Promise<any>
+  handler: OnNewAnrIssuePublishedHandler
 ): CloudFunction<CrashlyticsEvent<NewAnrIssuePayload>>;
 
 /**
@@ -556,11 +574,8 @@ export function onNewAnrIssuePublished(
  * @returns A function that you can export and deploy.
  */
 export function onNewAnrIssuePublished(
-  appIdOrOptsOrHandler:
-    | string
-    | CrashlyticsOptions
-    | ((event: CrashlyticsEvent<NewAnrIssuePayload>) => any | Promise<any>),
-  handler?: (event: CrashlyticsEvent<NewAnrIssuePayload>) => any | Promise<any>
+  appIdOrOptsOrHandler: string | CrashlyticsOptions | OnNewAnrIssuePublishedHandler,
+  handler?: OnNewAnrIssuePublishedHandler
 ): CloudFunction<CrashlyticsEvent<NewAnrIssuePayload>> {
   return onOperation<NewAnrIssuePayload>(newAnrIssueAlert, appIdOrOptsOrHandler, handler);
 }
@@ -568,14 +583,11 @@ export function onNewAnrIssuePublished(
 /** @internal */
 export function onOperation<T>(
   alertType: string,
-  appIdOrOptsOrHandler:
-    | string
-    | CrashlyticsOptions
-    | ((event: CrashlyticsEvent<T>) => any | Promise<any>),
-  handler: (event: CrashlyticsEvent<T>) => any | Promise<any>
+  appIdOrOptsOrHandler: string | CrashlyticsOptions | OnCrashlyticsOperationHandler<T>,
+  handler: OnCrashlyticsOperationHandler<T>
 ): CloudFunction<CrashlyticsEvent<T>> {
   if (typeof appIdOrOptsOrHandler === "function") {
-    handler = appIdOrOptsOrHandler as (event: CrashlyticsEvent<T>) => any | Promise<any>;
+    handler = appIdOrOptsOrHandler as OnCrashlyticsOperationHandler<T>;
     appIdOrOptsOrHandler = {};
   }
 
diff --git a/src/v2/providers/alerts/performance.ts b/src/v2/providers/alerts/performance.ts
index 9ee3f7beb..a1935e9e3 100644
--- a/src/v2/providers/alerts/performance.ts
+++ b/src/v2/providers/alerts/performance.ts
@@ -82,13 +82,18 @@ export interface PerformanceOptions extends EventHandlerOptions {
   appId?: string;
 }
 
+/** Handler used by {@link onThresholdAlertPublished}. */
+export type OnThresholdAlertPublishedHandler = (
+  event: PerformanceEvent<ThresholdAlertPayload>
+) => any | Promise<any>;
+
 /**
  * Declares a function that can handle receiving performance threshold alerts.
  * @param handler - Event handler which is run every time a threshold alert is received.
  * @returns A function that you can export and deploy.
  */
 export function onThresholdAlertPublished(
-  handler: (event: PerformanceEvent<ThresholdAlertPayload>) => any | Promise<any>
+  handler: OnThresholdAlertPublishedHandler
 ): CloudFunction<PerformanceEvent<ThresholdAlertPayload>>;
 
 /**
@@ -99,7 +104,7 @@ export function onThresholdAlertPublished(
  */
 export function onThresholdAlertPublished(
   appId: string,
-  handler: (event: PerformanceEvent<ThresholdAlertPayload>) => any | Promise<any>
+  handler: OnThresholdAlertPublishedHandler
 ): CloudFunction<PerformanceEvent<ThresholdAlertPayload>>;
 
 /**
@@ -110,7 +115,7 @@ export function onThresholdAlertPublished(
  */
 export function onThresholdAlertPublished(
   opts: PerformanceOptions,
-  handler: (event: PerformanceEvent<ThresholdAlertPayload>) => any | Promise<any>
+  handler: OnThresholdAlertPublishedHandler
 ): CloudFunction<PerformanceEvent<ThresholdAlertPayload>>;
 
 /**
@@ -120,11 +125,8 @@ export function onThresholdAlertPublished(
  * @returns A function that you can export and deploy.
  */
 export function onThresholdAlertPublished(
-  appIdOrOptsOrHandler:
-    | string
-    | PerformanceOptions
-    | ((event: PerformanceEvent<ThresholdAlertPayload>) => any | Promise<any>),
-  handler?: (event: PerformanceEvent<ThresholdAlertPayload>) => any | Promise<any>
+  appIdOrOptsOrHandler: string | PerformanceOptions | OnThresholdAlertPublishedHandler,
+  handler?: OnThresholdAlertPublishedHandler
 ): CloudFunction<PerformanceEvent<ThresholdAlertPayload>> {
   if (typeof appIdOrOptsOrHandler === "function") {
     handler = appIdOrOptsOrHandler as (
diff --git a/src/v2/providers/database.ts b/src/v2/providers/database.ts
index 6c5f5e83c..a3311cc3e 100644
--- a/src/v2/providers/database.ts
+++ b/src/v2/providers/database.ts
@@ -218,6 +218,48 @@ export interface ReferenceOptions<Ref extends string = string> extends options.E
   retry?: boolean | Expression<boolean> | ResetValue;
 }
 
+/** Handler used by {@link onValueWritten}. */
+export type OnValueWrittenHandler<Ref extends string = string> = (
+  event: DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onValueWritten} when accessing v1-compatible fields. */
+export type OnValueWrittenHandlerWithContext<Ref extends string = string> = (
+  event: DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>> &
+    V1Compat<"change", Change<DataSnapshot>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onValueCreated}. */
+export type OnValueCreatedHandler<Ref extends string = string> = (
+  event: DatabaseEvent<DataSnapshot, ParamsOf<Ref>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onValueCreated} when accessing v1-compatible fields. */
+export type OnValueCreatedHandlerWithContext<Ref extends string = string> = (
+  event: DatabaseEvent<DataSnapshot, ParamsOf<Ref>> & V1Compat<"snapshot", DataSnapshot>
+) => any | Promise<any>;
+
+/** Handler used by {@link onValueUpdated}. */
+export type OnValueUpdatedHandler<Ref extends string = string> = OnValueWrittenHandler<Ref>;
+
+/** Handler used by {@link onValueUpdated} when accessing v1-compatible fields. */
+export type OnValueUpdatedHandlerWithContext<Ref extends string = string> =
+  OnValueWrittenHandlerWithContext<Ref>;
+
+/** Handler used by {@link onValueDeleted}. */
+export type OnValueDeletedHandler<Ref extends string = string> = OnValueCreatedHandler<Ref>;
+
+/** Handler used by {@link onValueDeleted} when accessing v1-compatible fields. */
+export type OnValueDeletedHandlerWithContext<Ref extends string = string> =
+  OnValueCreatedHandlerWithContext<Ref>;
+
+/** Handler used by internal changed Realtime Database operations. */
+export type OnChangedOperationHandler<Ref extends string = string> =
+  OnValueWrittenHandlerWithContext<Ref>;
+
+/** Handler used by internal Realtime Database operations. */
+export type OnOperationHandler<Ref extends string = string> = OnValueCreatedHandlerWithContext<Ref>;
+
 /**
  * Event handler which triggers when data is created, updated, or deleted in Realtime Database.
  *
@@ -226,10 +268,7 @@ export interface ReferenceOptions<Ref extends string = string> extends options.E
  */
 export function onValueWritten<Ref extends string>(
   reference: Ref,
-  handler: (
-    event: DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>> &
-      V1Compat<"change", Change<DataSnapshot>>
-  ) => any | Promise<any>
+  handler: OnValueWrittenHandlerWithContext<Ref>
 ): CloudFunction<DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>>;
 
 /**
@@ -240,7 +279,7 @@ export function onValueWritten<Ref extends string>(
  */
 export function onValueWritten<Ref extends string>(
   reference: Ref,
-  handler: (event: DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>) => any | Promise<any>
+  handler: OnValueWrittenHandler<Ref>
 ): CloudFunction<DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>>;
 
 /**
@@ -251,10 +290,7 @@ export function onValueWritten<Ref extends string>(
  */
 export function onValueWritten<Ref extends string>(
   opts: ReferenceOptions<Ref>,
-  handler: (
-    event: DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>> &
-      V1Compat<"change", Change<DataSnapshot>>
-  ) => any | Promise<any>
+  handler: OnValueWrittenHandlerWithContext<Ref>
 ): CloudFunction<DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>>;
 
 /**
@@ -265,7 +301,7 @@ export function onValueWritten<Ref extends string>(
  */
 export function onValueWritten<Ref extends string>(
   opts: ReferenceOptions<Ref>,
-  handler: (event: DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>) => any | Promise<any>
+  handler: OnValueWrittenHandler<Ref>
 ): CloudFunction<DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>>;
 
 /**
@@ -276,10 +312,7 @@ export function onValueWritten<Ref extends string>(
  */
 export function onValueWritten<Ref extends string>(
   referenceOrOpts: Ref | ReferenceOptions<Ref>,
-  handler: (
-    event: DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>> &
-      V1Compat<"change", Change<DataSnapshot>>
-  ) => any | Promise<any>
+  handler: OnValueWrittenHandlerWithContext<Ref>
 ): CloudFunction<DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>> {
   return onChangedOperation(writtenEventType, referenceOrOpts, handler);
 }
@@ -292,9 +325,7 @@ export function onValueWritten<Ref extends string>(
  */
 export function onValueCreated<Ref extends string>(
   reference: Ref,
-  handler: (
-    event: DatabaseEvent<DataSnapshot, ParamsOf<Ref>> & V1Compat<"snapshot", DataSnapshot>
-  ) => any | Promise<any>
+  handler: OnValueCreatedHandlerWithContext<Ref>
 ): CloudFunction<DatabaseEvent<DataSnapshot, ParamsOf<Ref>>>;
 
 /**
@@ -305,7 +336,7 @@ export function onValueCreated<Ref extends string>(
  */
 export function onValueCreated<Ref extends string>(
   reference: Ref,
-  handler: (event: DatabaseEvent<DataSnapshot, ParamsOf<Ref>>) => any | Promise<any>
+  handler: OnValueCreatedHandler<Ref>
 ): CloudFunction<DatabaseEvent<DataSnapshot, ParamsOf<Ref>>>;
 
 /**
@@ -316,9 +347,7 @@ export function onValueCreated<Ref extends string>(
  */
 export function onValueCreated<Ref extends string>(
   opts: ReferenceOptions<Ref>,
-  handler: (
-    event: DatabaseEvent<DataSnapshot, ParamsOf<Ref>> & V1Compat<"snapshot", DataSnapshot>
-  ) => any | Promise<any>
+  handler: OnValueCreatedHandlerWithContext<Ref>
 ): CloudFunction<DatabaseEvent<DataSnapshot, ParamsOf<Ref>>>;
 
 /**
@@ -329,7 +358,7 @@ export function onValueCreated<Ref extends string>(
  */
 export function onValueCreated<Ref extends string>(
   opts: ReferenceOptions<Ref>,
-  handler: (event: DatabaseEvent<DataSnapshot, ParamsOf<Ref>>) => any | Promise<any>
+  handler: OnValueCreatedHandler<Ref>
 ): CloudFunction<DatabaseEvent<DataSnapshot, ParamsOf<Ref>>>;
 
 /**
@@ -340,9 +369,7 @@ export function onValueCreated<Ref extends string>(
  */
 export function onValueCreated<Ref extends string>(
   referenceOrOpts: Ref | ReferenceOptions<Ref>,
-  handler: (
-    event: DatabaseEvent<DataSnapshot, ParamsOf<Ref>> & V1Compat<"snapshot", DataSnapshot>
-  ) => any | Promise<any>
+  handler: OnValueCreatedHandlerWithContext<Ref>
 ): CloudFunction<DatabaseEvent<DataSnapshot, ParamsOf<Ref>>> {
   return onOperation(createdEventType, referenceOrOpts, handler);
 }
@@ -355,10 +382,7 @@ export function onValueCreated<Ref extends string>(
  */
 export function onValueUpdated<Ref extends string>(
   reference: Ref,
-  handler: (
-    event: DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>> &
-      V1Compat<"change", Change<DataSnapshot>>
-  ) => any | Promise<any>
+  handler: OnValueUpdatedHandlerWithContext<Ref>
 ): CloudFunction<DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>>;
 
 /**
@@ -369,7 +393,7 @@ export function onValueUpdated<Ref extends string>(
  */
 export function onValueUpdated<Ref extends string>(
   reference: Ref,
-  handler: (event: DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>) => any | Promise<any>
+  handler: OnValueUpdatedHandler<Ref>
 ): CloudFunction<DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>>;
 
 /**
@@ -380,10 +404,7 @@ export function onValueUpdated<Ref extends string>(
  */
 export function onValueUpdated<Ref extends string>(
   opts: ReferenceOptions<Ref>,
-  handler: (
-    event: DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>> &
-      V1Compat<"change", Change<DataSnapshot>>
-  ) => any | Promise<any>
+  handler: OnValueUpdatedHandlerWithContext<Ref>
 ): CloudFunction<DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>>;
 
 /**
@@ -394,7 +415,7 @@ export function onValueUpdated<Ref extends string>(
  */
 export function onValueUpdated<Ref extends string>(
   opts: ReferenceOptions<Ref>,
-  handler: (event: DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>) => any | Promise<any>
+  handler: OnValueUpdatedHandler<Ref>
 ): CloudFunction<DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>>;
 
 /**
@@ -405,10 +426,7 @@ export function onValueUpdated<Ref extends string>(
  */
 export function onValueUpdated<Ref extends string>(
   referenceOrOpts: Ref | ReferenceOptions<Ref>,
-  handler: (
-    event: DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>> &
-      V1Compat<"change", Change<DataSnapshot>>
-  ) => any | Promise<any>
+  handler: OnValueUpdatedHandlerWithContext<Ref>
 ): CloudFunction<DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>> {
   return onChangedOperation(updatedEventType, referenceOrOpts, handler);
 }
@@ -421,9 +439,7 @@ export function onValueUpdated<Ref extends string>(
  */
 export function onValueDeleted<Ref extends string>(
   reference: Ref,
-  handler: (
-    event: DatabaseEvent<DataSnapshot, ParamsOf<Ref>> & V1Compat<"snapshot", DataSnapshot>
-  ) => any | Promise<any>
+  handler: OnValueDeletedHandlerWithContext<Ref>
 ): CloudFunction<DatabaseEvent<DataSnapshot, ParamsOf<Ref>>>;
 
 /**
@@ -434,7 +450,7 @@ export function onValueDeleted<Ref extends string>(
  */
 export function onValueDeleted<Ref extends string>(
   reference: Ref,
-  handler: (event: DatabaseEvent<DataSnapshot, ParamsOf<Ref>>) => any | Promise<any>
+  handler: OnValueDeletedHandler<Ref>
 ): CloudFunction<DatabaseEvent<DataSnapshot, ParamsOf<Ref>>>;
 
 /**
@@ -445,9 +461,7 @@ export function onValueDeleted<Ref extends string>(
  */
 export function onValueDeleted<Ref extends string>(
   opts: ReferenceOptions<Ref>,
-  handler: (
-    event: DatabaseEvent<DataSnapshot, ParamsOf<Ref>> & V1Compat<"snapshot", DataSnapshot>
-  ) => any | Promise<any>
+  handler: OnValueDeletedHandlerWithContext<Ref>
 ): CloudFunction<DatabaseEvent<DataSnapshot, ParamsOf<Ref>>>;
 
 /**
@@ -458,7 +472,7 @@ export function onValueDeleted<Ref extends string>(
  */
 export function onValueDeleted<Ref extends string>(
   opts: ReferenceOptions<Ref>,
-  handler: (event: DatabaseEvent<DataSnapshot, ParamsOf<Ref>>) => any | Promise<any>
+  handler: OnValueDeletedHandler<Ref>
 ): CloudFunction<DatabaseEvent<DataSnapshot, ParamsOf<Ref>>>;
 
 /**
@@ -469,9 +483,7 @@ export function onValueDeleted<Ref extends string>(
  */
 export function onValueDeleted<Ref extends string>(
   referenceOrOpts: Ref | ReferenceOptions<Ref>,
-  handler: (
-    event: DatabaseEvent<DataSnapshot, ParamsOf<Ref>> & V1Compat<"snapshot", DataSnapshot>
-  ) => any | Promise<any>
+  handler: OnValueDeletedHandlerWithContext<Ref>
 ): CloudFunction<DatabaseEvent<DataSnapshot, ParamsOf<Ref>>> {
   // TODO - need to use event.data.delta
   return onOperation(deletedEventType, referenceOrOpts, handler);
@@ -636,7 +648,7 @@ export function makeEndpoint(
 export function onChangedOperation<Ref extends string>(
   eventType: string,
   referenceOrOpts: Ref | ReferenceOptions<Ref>,
-  handler: (event: any) => any | Promise<any>
+  handler: OnChangedOperationHandler<Ref>
 ): CloudFunction<DatabaseEvent<Change<DataSnapshot>, ParamsOf<Ref>>> {
   const { path, instance, opts } = getOpts(referenceOrOpts);
 
@@ -671,7 +683,7 @@ export function onChangedOperation<Ref extends string>(
 export function onOperation<Ref extends string>(
   eventType: string,
   referenceOrOpts: Ref | ReferenceOptions<Ref>,
-  handler: (event: any) => any | Promise<any>
+  handler: OnOperationHandler<Ref>
 ): CloudFunction<DatabaseEvent<DataSnapshot, ParamsOf<Ref>>> {
   const { path, instance, opts } = getOpts(referenceOrOpts);
 
diff --git a/src/v2/providers/dataconnect/index.ts b/src/v2/providers/dataconnect/index.ts
index 5d88dd2bd..452878f68 100644
--- a/src/v2/providers/dataconnect/index.ts
+++ b/src/v2/providers/dataconnect/index.ts
@@ -139,6 +139,18 @@ export interface DataConnectEvent<T, Params extends Record<never, string>> exten
   authId?: string;
 }
 
+/** Handler used by {@link onMutationExecuted}. */
+export type OnMutationExecutedHandler<
+  PathPatternOrOptions extends string | OperationOptions<string, string, string>,
+  Variables = unknown,
+  ResponseData = unknown
+> = (
+  event: DataConnectEvent<
+    MutationEventData<Variables, ResponseData>,
+    DataConnectParams<PathPatternOrOptions>
+  >
+) => unknown | Promise<unknown>;
+
 /**
  * Event handler that triggers when a mutation is executed in Firebase Data Connect.
  *
@@ -151,9 +163,7 @@ export function onMutationExecuted<
   ResponseData = unknown
 >(
   mutation: Mutation,
-  handler: (
-    event: DataConnectEvent<MutationEventData<Variables, ResponseData>, DataConnectParams<Mutation>>
-  ) => unknown | Promise<unknown>
+  handler: OnMutationExecutedHandler<Mutation, Variables, ResponseData>
 ): CloudFunction<
   DataConnectEvent<MutationEventData<Variables, ResponseData>, DataConnectParams<Mutation>>
 >;
@@ -170,9 +180,7 @@ export function onMutationExecuted<
   ResponseData = unknown
 >(
   opts: Options,
-  handler: (
-    event: DataConnectEvent<MutationEventData<Variables, ResponseData>, DataConnectParams<Options>>
-  ) => unknown | Promise<unknown>
+  handler: OnMutationExecutedHandler<Options, Variables, ResponseData>
 ): CloudFunction<
   DataConnectEvent<MutationEventData<Variables, ResponseData>, DataConnectParams<Options>>
 >;
@@ -189,12 +197,7 @@ export function onMutationExecuted<
   ResponseData = unknown
 >(
   mutationOrOpts: PathPatternOrOptions,
-  handler: (
-    event: DataConnectEvent<
-      MutationEventData<Variables, ResponseData>,
-      DataConnectParams<PathPatternOrOptions>
-    >
-  ) => unknown | Promise<unknown>
+  handler: OnMutationExecutedHandler<PathPatternOrOptions, Variables, ResponseData>
 ): CloudFunction<
   DataConnectEvent<
     MutationEventData<Variables, ResponseData>,
diff --git a/src/v2/providers/eventarc.ts b/src/v2/providers/eventarc.ts
index f00597bab..36ffaff38 100644
--- a/src/v2/providers/eventarc.ts
+++ b/src/v2/providers/eventarc.ts
@@ -162,6 +162,9 @@ export interface EventarcTriggerOptions extends options.EventHandlerOptions {
   retry?: boolean | Expression<boolean> | ResetValue;
 }
 
+/** Handler used by {@link onCustomEventPublished}. */
+export type OnCustomEventPublishedHandler<T = any> = (event: CloudEvent<T>) => any | Promise<any>;
+
 /** Handles an Eventarc event published on the default channel.
  * @param eventType - Type of the event to trigger on.
  * @param handler - A function to execute when triggered.
@@ -169,7 +172,7 @@ export interface EventarcTriggerOptions extends options.EventHandlerOptions {
  */
 export function onCustomEventPublished<T = any>(
   eventType: string,
-  handler: (event: CloudEvent<T>) => any | Promise<any>
+  handler: OnCustomEventPublishedHandler<T>
 ): CloudFunction<CloudEvent<T>>;
 
 /** Handles an Eventarc event.
@@ -179,12 +182,12 @@ export function onCustomEventPublished<T = any>(
  */
 export function onCustomEventPublished<T = any>(
   opts: EventarcTriggerOptions,
-  handler: (event: CloudEvent<T>) => any | Promise<any>
+  handler: OnCustomEventPublishedHandler<T>
 ): CloudFunction<CloudEvent<T>>;
 
 export function onCustomEventPublished<T = any>(
   eventTypeOrOpts: string | EventarcTriggerOptions,
-  handler: (event: CloudEvent<T>) => any | Promise<any>
+  handler: OnCustomEventPublishedHandler<T>
 ): CloudFunction<CloudEvent<T>> {
   let opts: EventarcTriggerOptions;
   if (typeof eventTypeOrOpts === "string") {
diff --git a/src/v2/providers/firestore.ts b/src/v2/providers/firestore.ts
index a7b7ffb81..6acd9c05d 100644
--- a/src/v2/providers/firestore.ts
+++ b/src/v2/providers/firestore.ts
@@ -155,6 +155,94 @@ export interface DocumentOptions<Document extends string = string> extends Event
   namespace?: string | Expression<string>;
 }
 
+/** Handler used by {@link onDocumentWritten}. */
+export type OnDocumentWrittenHandler<Document extends string = string> = (
+  event: FirestoreEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onDocumentWritten} when accessing v1-compatible fields. */
+export type OnDocumentWrittenHandlerWithContext<Document extends string = string> = (
+  event: FirestoreEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>> &
+    V1Compat<"change", Change<DocumentSnapshot>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onDocumentWrittenWithAuthContext}. */
+export type OnDocumentWrittenWithAuthContextHandler<Document extends string = string> = (
+  event: FirestoreAuthEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onDocumentWrittenWithAuthContext} when accessing v1-compatible fields. */
+export type OnDocumentWrittenWithAuthContextHandlerWithContext<Document extends string = string> = (
+  event: FirestoreAuthEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>> &
+    V1Compat<"change", Change<DocumentSnapshot>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onDocumentCreated}. */
+export type OnDocumentCreatedHandler<Document extends string = string> = (
+  event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onDocumentCreated} when accessing v1-compatible fields. */
+export type OnDocumentCreatedHandlerWithContext<Document extends string = string> = (
+  event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
+    V1Compat<"snapshot", QueryDocumentSnapshot>
+) => any | Promise<any>;
+
+/** Handler used by {@link onDocumentCreatedWithAuthContext}. */
+export type OnDocumentCreatedWithAuthContextHandler<Document extends string = string> = (
+  event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onDocumentCreatedWithAuthContext} when accessing v1-compatible fields. */
+export type OnDocumentCreatedWithAuthContextHandlerWithContext<Document extends string = string> = (
+  event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
+    V1Compat<"snapshot", QueryDocumentSnapshot>
+) => any | Promise<any>;
+
+/** Handler used by {@link onDocumentUpdated}. */
+export type OnDocumentUpdatedHandler<Document extends string = string> = (
+  event: FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onDocumentUpdated} when accessing v1-compatible fields. */
+export type OnDocumentUpdatedHandlerWithContext<Document extends string = string> = (
+  event: FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>> &
+    V1Compat<"change", Change<QueryDocumentSnapshot>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onDocumentUpdatedWithAuthContext}. */
+export type OnDocumentUpdatedWithAuthContextHandler<Document extends string = string> = (
+  event: FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onDocumentUpdatedWithAuthContext} when accessing v1-compatible fields. */
+export type OnDocumentUpdatedWithAuthContextHandlerWithContext<Document extends string = string> = (
+  event: FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>> &
+    V1Compat<"change", Change<QueryDocumentSnapshot>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onDocumentDeleted}. */
+export type OnDocumentDeletedHandler<Document extends string = string> =
+  OnDocumentCreatedHandler<Document>;
+
+/** Handler used by {@link onDocumentDeleted} when accessing v1-compatible fields. */
+export type OnDocumentDeletedHandlerWithContext<Document extends string = string> =
+  OnDocumentCreatedHandlerWithContext<Document>;
+
+/** Handler used by {@link onDocumentDeletedWithAuthContext}. */
+export type OnDocumentDeletedWithAuthContextHandler<Document extends string = string> =
+  OnDocumentCreatedWithAuthContextHandler<Document>;
+
+/** Handler used by {@link onDocumentDeletedWithAuthContext} when accessing v1-compatible fields. */
+export type OnDocumentDeletedWithAuthContextHandlerWithContext<Document extends string = string> =
+  OnDocumentCreatedWithAuthContextHandlerWithContext<Document>;
+
+/** Handler used by internal Firestore operations. */
+export type OnOperationHandler<Event> = (event: Event) => any | Promise<any>;
+
+/** Handler used by internal changed Firestore operations. */
+export type OnChangedOperationHandler<Event> = (event: Event) => any | Promise<any>;
+
 /**
  * Event handler that triggers when a document is created, updated, or deleted in Firestore.
  *
@@ -163,10 +251,7 @@ export interface DocumentOptions<Document extends string = string> extends Event
  */
 export function onDocumentWritten<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<DocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentWrittenHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -177,9 +262,7 @@ export function onDocumentWritten<Document extends string>(
  */
 export function onDocumentWritten<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentWrittenHandler<Document>
 ): CloudFunction<FirestoreEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -190,10 +273,7 @@ export function onDocumentWritten<Document extends string>(
  */
 export function onDocumentWritten<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<DocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentWrittenHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -204,9 +284,7 @@ export function onDocumentWritten<Document extends string>(
  */
 export function onDocumentWritten<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentWrittenHandler<Document>
 ): CloudFunction<FirestoreEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -217,10 +295,7 @@ export function onDocumentWritten<Document extends string>(
  */
 export function onDocumentWritten<Document extends string>(
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<DocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentWrittenHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>> {
   return onChangedOperation(writtenEventType, documentOrOpts, handler);
 }
@@ -234,10 +309,7 @@ export function onDocumentWritten<Document extends string>(
  */
 export function onDocumentWrittenWithAuthContext<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreAuthEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<DocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentWrittenWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -249,9 +321,7 @@ export function onDocumentWrittenWithAuthContext<Document extends string>(
  */
 export function onDocumentWrittenWithAuthContext<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreAuthEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentWrittenWithAuthContextHandler<Document>
 ): CloudFunction<FirestoreAuthEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -263,10 +333,7 @@ export function onDocumentWrittenWithAuthContext<Document extends string>(
  */
 export function onDocumentWrittenWithAuthContext<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<DocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentWrittenWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -278,9 +345,7 @@ export function onDocumentWrittenWithAuthContext<Document extends string>(
  */
 export function onDocumentWrittenWithAuthContext<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentWrittenWithAuthContextHandler<Document>
 ): CloudFunction<FirestoreAuthEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -292,10 +357,7 @@ export function onDocumentWrittenWithAuthContext<Document extends string>(
  */
 export function onDocumentWrittenWithAuthContext<Document extends string>(
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<DocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentWrittenWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<Change<DocumentSnapshot> | undefined, ParamsOf<Document>>> {
   return onChangedOperation(writtenEventWithAuthContextType, documentOrOpts, handler);
 }
@@ -308,10 +370,7 @@ export function onDocumentWrittenWithAuthContext<Document extends string>(
  */
 export function onDocumentCreated<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -322,9 +381,7 @@ export function onDocumentCreated<Document extends string>(
  */
 export function onDocumentCreated<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedHandler<Document>
 ): CloudFunction<FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -335,10 +392,7 @@ export function onDocumentCreated<Document extends string>(
  */
 export function onDocumentCreated<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -349,9 +403,7 @@ export function onDocumentCreated<Document extends string>(
  */
 export function onDocumentCreated<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedHandler<Document>
 ): CloudFunction<FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -362,10 +414,7 @@ export function onDocumentCreated<Document extends string>(
  */
 export function onDocumentCreated<Document extends string>(
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>> {
   return onOperation(createdEventType, documentOrOpts, handler);
 }
@@ -379,10 +428,7 @@ export function onDocumentCreated<Document extends string>(
  */
 export function onDocumentCreatedWithAuthContext<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -394,9 +440,7 @@ export function onDocumentCreatedWithAuthContext<Document extends string>(
  */
 export function onDocumentCreatedWithAuthContext<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedWithAuthContextHandler<Document>
 ): CloudFunction<FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -408,10 +452,7 @@ export function onDocumentCreatedWithAuthContext<Document extends string>(
  */
 export function onDocumentCreatedWithAuthContext<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -423,9 +464,7 @@ export function onDocumentCreatedWithAuthContext<Document extends string>(
  */
 export function onDocumentCreatedWithAuthContext<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedWithAuthContextHandler<Document>
 ): CloudFunction<FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -436,10 +475,7 @@ export function onDocumentCreatedWithAuthContext<Document extends string>(
  */
 export function onDocumentCreatedWithAuthContext<Document extends string>(
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>> {
   return onOperation(createdEventWithAuthContextType, documentOrOpts, handler);
 }
@@ -452,10 +488,7 @@ export function onDocumentCreatedWithAuthContext<Document extends string>(
  */
 export function onDocumentUpdated<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<QueryDocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -466,9 +499,7 @@ export function onDocumentUpdated<Document extends string>(
  */
 export function onDocumentUpdated<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedHandler<Document>
 ): CloudFunction<FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -479,10 +510,7 @@ export function onDocumentUpdated<Document extends string>(
  */
 export function onDocumentUpdated<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<QueryDocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -493,9 +521,7 @@ export function onDocumentUpdated<Document extends string>(
  */
 export function onDocumentUpdated<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedHandler<Document>
 ): CloudFunction<FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -506,10 +532,7 @@ export function onDocumentUpdated<Document extends string>(
  */
 export function onDocumentUpdated<Document extends string>(
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<QueryDocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>> {
   return onChangedOperation(updatedEventType, documentOrOpts, handler);
 }
@@ -523,10 +546,7 @@ export function onDocumentUpdated<Document extends string>(
  */
 export function onDocumentUpdatedWithAuthContext<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<QueryDocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -538,9 +558,7 @@ export function onDocumentUpdatedWithAuthContext<Document extends string>(
  */
 export function onDocumentUpdatedWithAuthContext<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedWithAuthContextHandler<Document>
 ): CloudFunction<FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -552,10 +570,7 @@ export function onDocumentUpdatedWithAuthContext<Document extends string>(
  */
 export function onDocumentUpdatedWithAuthContext<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<QueryDocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -567,9 +582,7 @@ export function onDocumentUpdatedWithAuthContext<Document extends string>(
  */
 export function onDocumentUpdatedWithAuthContext<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedWithAuthContextHandler<Document>
 ): CloudFunction<FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 /**
@@ -580,10 +593,7 @@ export function onDocumentUpdatedWithAuthContext<Document extends string>(
  */
 export function onDocumentUpdatedWithAuthContext<Document extends string>(
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<QueryDocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<
   FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>
 > {
@@ -598,10 +608,7 @@ export function onDocumentUpdatedWithAuthContext<Document extends string>(
  */
 export function onDocumentDeleted<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentDeletedHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -612,9 +619,7 @@ export function onDocumentDeleted<Document extends string>(
  */
 export function onDocumentDeleted<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentDeletedHandler<Document>
 ): CloudFunction<FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -625,10 +630,7 @@ export function onDocumentDeleted<Document extends string>(
  */
 export function onDocumentDeleted<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentDeletedHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -639,9 +641,7 @@ export function onDocumentDeleted<Document extends string>(
  */
 export function onDocumentDeleted<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentDeletedHandler<Document>
 ): CloudFunction<FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -652,10 +652,7 @@ export function onDocumentDeleted<Document extends string>(
  */
 export function onDocumentDeleted<Document extends string>(
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentDeletedHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>> {
   return onOperation(deletedEventType, documentOrOpts, handler);
 }
@@ -669,10 +666,7 @@ export function onDocumentDeleted<Document extends string>(
  */
 export function onDocumentDeletedWithAuthContext<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentDeletedWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -684,9 +678,7 @@ export function onDocumentDeletedWithAuthContext<Document extends string>(
  */
 export function onDocumentDeletedWithAuthContext<Document extends string>(
   document: Document,
-  handler: (
-    event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentDeletedWithAuthContextHandler<Document>
 ): CloudFunction<FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -698,10 +690,7 @@ export function onDocumentDeletedWithAuthContext<Document extends string>(
  */
 export function onDocumentDeletedWithAuthContext<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentDeletedWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -713,9 +702,7 @@ export function onDocumentDeletedWithAuthContext<Document extends string>(
  */
 export function onDocumentDeletedWithAuthContext<Document extends string>(
   opts: DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentDeletedWithAuthContextHandler<Document>
 ): CloudFunction<FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 /**
@@ -726,10 +713,7 @@ export function onDocumentDeletedWithAuthContext<Document extends string>(
  */
 export function onDocumentDeletedWithAuthContext<Document extends string>(
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentDeletedWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>> {
   return onOperation(deletedEventWithAuthContextType, documentOrOpts, handler);
 }
@@ -970,35 +954,25 @@ export function getV1Context(event: any) {
 export function onOperation<Document extends string>(
   eventType: string,
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 export function onOperation<Document extends string>(
   eventType: string,
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedHandler<Document>
 ): CloudFunction<FirestoreEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 export function onOperation<Document extends string>(
   eventType: string,
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>> &
-      V1Compat<"snapshot", QueryDocumentSnapshot>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 export function onOperation<Document extends string>(
   eventType: string,
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentCreatedWithAuthContextHandler<Document>
 ): CloudFunction<FirestoreAuthEvent<QueryDocumentSnapshot | undefined, ParamsOf<Document>>>;
 
 export function onOperation<
@@ -1013,7 +987,7 @@ export function onOperation<
 >(
   eventType: string,
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (event: Event) => any | Promise<any>
+  handler: OnOperationHandler<Event>
 ): CloudFunction<Event> {
   const { document, database, namespace, opts } = getOpts(documentOrOpts);
 
@@ -1045,35 +1019,25 @@ export function onOperation<
 export function onChangedOperation<Document extends string>(
   eventType: string,
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<QueryDocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedHandlerWithContext<Document>
 ): CloudFunction<FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 export function onChangedOperation<Document extends string>(
   eventType: string,
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedHandler<Document>
 ): CloudFunction<FirestoreEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 export function onChangedOperation<Document extends string>(
   eventType: string,
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>> &
-      V1Compat<"change", Change<QueryDocumentSnapshot>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedWithAuthContextHandlerWithContext<Document>
 ): CloudFunction<FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 export function onChangedOperation<Document extends string>(
   eventType: string,
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (
-    event: FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>
-  ) => any | Promise<any>
+  handler: OnDocumentUpdatedWithAuthContextHandler<Document>
 ): CloudFunction<FirestoreAuthEvent<Change<QueryDocumentSnapshot> | undefined, ParamsOf<Document>>>;
 
 export function onChangedOperation<
@@ -1088,7 +1052,7 @@ export function onChangedOperation<
 >(
   eventType: string,
   documentOrOpts: Document | DocumentOptions<Document>,
-  handler: (event: Event) => any | Promise<any>
+  handler: OnChangedOperationHandler<Event>
 ): CloudFunction<Event> {
   const { document, database, namespace, opts } = getOpts(documentOrOpts);
 
diff --git a/src/v2/providers/https.ts b/src/v2/providers/https.ts
index cfb3cfee3..4fae6a0fe 100644
--- a/src/v2/providers/https.ts
+++ b/src/v2/providers/https.ts
@@ -286,29 +286,34 @@ export interface CallableFunction<T, Return, Stream = unknown> extends HttpsFunc
   ): { stream: AsyncIterable<Stream>; output: Return };
 }
 
+/** Handler used by {@link onRequest}. */
+export type OnRequestHandler = (
+  request: Request,
+  response: express.Response
+) => void | Promise<void>;
+
+/** Handler used by {@link onCall}. */
+export type OnCallHandler<T = any, Return = any | Promise<any>, Stream = unknown> = (
+  request: CallableRequest<T>,
+  response?: CallableResponse<Stream>
+) => Return;
+
 /**
  * Handles HTTPS requests.
  * @param opts - Options to set on this function
  * @param handler - A function that takes a {@link https.Request} and response object, same signature as an Express app.
  * @returns A function that you can export and deploy.
  */
-export function onRequest(
-  opts: HttpsOptions,
-  handler: (request: Request, response: express.Response) => void | Promise<void>
-): HttpsFunction;
+export function onRequest(opts: HttpsOptions, handler: OnRequestHandler): HttpsFunction;
 /**
  * Handles HTTPS requests.
  * @param handler - A function that takes a {@link https.Request} and response object, same signature as an Express app.
  * @returns A function that you can export and deploy.
  */
+export function onRequest(handler: OnRequestHandler): HttpsFunction;
 export function onRequest(
-  handler: (request: Request, response: express.Response) => void | Promise<void>
-): HttpsFunction;
-export function onRequest(
-  optsOrHandler:
-    | HttpsOptions
-    | ((request: Request, response: express.Response) => void | Promise<void>),
-  handler?: (request: Request, response: express.Response) => void | Promise<void>
+  optsOrHandler: HttpsOptions | OnRequestHandler,
+  handler?: OnRequestHandler
 ): HttpsFunction {
   let opts: HttpsOptions;
   if (arguments.length === 1) {
@@ -411,7 +416,7 @@ export function onRequest(
  */
 export function onCall<T = any, Return = any | Promise<any>, Stream = unknown>(
   opts: CallableOptions<T>,
-  handler: (request: CallableRequest<T>, response?: CallableResponse<Stream>) => Return
+  handler: OnCallHandler<T, Return, Stream>
 ): CallableFunction<T, Return extends Promise<unknown> ? Return : Promise<Return>, Stream>;
 
 /**
@@ -420,11 +425,11 @@ export function onCall<T = any, Return = any | Promise<any>, Stream = unknown>(
  * @returns A function that you can export and deploy.
  */
 export function onCall<T = any, Return = any | Promise<any>, Stream = unknown>(
-  handler: (request: CallableRequest<T>, response?: CallableResponse<Stream>) => Return
+  handler: OnCallHandler<T, Return, Stream>
 ): CallableFunction<T, Return extends Promise<unknown> ? Return : Promise<Return>>;
 export function onCall<T = any, Return = any | Promise<any>, Stream = unknown>(
-  optsOrHandler: CallableOptions<T> | ((request: CallableRequest<T>) => Return),
-  handler?: (request: CallableRequest<T>, response?: CallableResponse<Stream>) => Return
+  optsOrHandler: CallableOptions<T> | OnCallHandler<T, Return, Stream>,
+  handler?: OnCallHandler<T, Return, Stream>
 ): CallableFunction<T, Return extends Promise<unknown> ? Return : Promise<Return>> {
   let opts: CallableOptions;
   if (arguments.length === 1) {
diff --git a/src/v2/providers/identity.ts b/src/v2/providers/identity.ts
index 2e46b6779..95e955338 100644
--- a/src/v2/providers/identity.ts
+++ b/src/v2/providers/identity.ts
@@ -166,13 +166,31 @@ export interface BlockingOptions {
   secrets?: SupportedSecretParam[];
 }
 
+/** Handler used by {@link beforeUserCreated}. */
+export type BeforeUserCreatedHandler = (
+  event: AuthBlockingEvent
+) => MaybeAsync<BeforeCreateResponse | void>;
+
+/** Handler used by {@link beforeUserSignedIn}. */
+export type BeforeUserSignedInHandler = (
+  event: AuthBlockingEvent
+) => MaybeAsync<BeforeSignInResponse | void>;
+
+/** Handler used by {@link beforeEmailSent}. */
+export type BeforeEmailSentHandler = (
+  event: AuthBlockingEvent
+) => MaybeAsync<BeforeEmailResponse | void>;
+
+/** Handler used by {@link beforeSmsSent}. */
+export type BeforeSmsSentHandler = (
+  event: AuthBlockingEvent
+) => MaybeAsync<BeforeSmsResponse | void>;
+
 /**
  * Handles an event that is triggered before a user is created.
  * @param handler - Event handler which is run every time before a user is created.
  */
-export function beforeUserCreated(
-  handler: (event: AuthBlockingEvent) => MaybeAsync<BeforeCreateResponse | void>
-): BlockingFunction;
+export function beforeUserCreated(handler: BeforeUserCreatedHandler): BlockingFunction;
 
 /**
  * Handles an event that is triggered before a user is created.
@@ -181,7 +199,7 @@ export function beforeUserCreated(
  */
 export function beforeUserCreated(
   opts: BlockingOptions,
-  handler: (event: AuthBlockingEvent) => MaybeAsync<BeforeCreateResponse | void>
+  handler: BeforeUserCreatedHandler
 ): BlockingFunction;
 
 /**
@@ -190,10 +208,8 @@ export function beforeUserCreated(
  * @param handler? - If defined, an event handler which is run every time before a user is created.
  */
 export function beforeUserCreated(
-  optsOrHandler:
-    | BlockingOptions
-    | ((event: AuthBlockingEvent) => MaybeAsync<BeforeCreateResponse | void>),
-  handler?: (event: AuthBlockingEvent) => MaybeAsync<BeforeCreateResponse | void>
+  optsOrHandler: BlockingOptions | BeforeUserCreatedHandler,
+  handler?: BeforeUserCreatedHandler
 ): BlockingFunction {
   return beforeOperation("beforeCreate", optsOrHandler, handler);
 }
@@ -202,9 +218,7 @@ export function beforeUserCreated(
  * Handles an event that is triggered before a user is signed in.
  * @param handler - Event handler which is run every time before a user is signed in.
  */
-export function beforeUserSignedIn(
-  handler: (event: AuthBlockingEvent) => MaybeAsync<BeforeSignInResponse | void>
-): BlockingFunction;
+export function beforeUserSignedIn(handler: BeforeUserSignedInHandler): BlockingFunction;
 
 /**
  * Handles an event that is triggered before a user is signed in.
@@ -213,7 +227,7 @@ export function beforeUserSignedIn(
  */
 export function beforeUserSignedIn(
   opts: BlockingOptions,
-  handler: (event: AuthBlockingEvent) => MaybeAsync<BeforeSignInResponse | void>
+  handler: BeforeUserSignedInHandler
 ): BlockingFunction;
 
 /**
@@ -222,10 +236,8 @@ export function beforeUserSignedIn(
  * @param handler - Event handler which is run every time before a user is signed in.
  */
 export function beforeUserSignedIn(
-  optsOrHandler:
-    | BlockingOptions
-    | ((event: AuthBlockingEvent) => MaybeAsync<BeforeSignInResponse | void>),
-  handler?: (event: AuthBlockingEvent) => MaybeAsync<BeforeSignInResponse | void>
+  optsOrHandler: BlockingOptions | BeforeUserSignedInHandler,
+  handler?: BeforeUserSignedInHandler
 ): BlockingFunction {
   return beforeOperation("beforeSignIn", optsOrHandler, handler);
 }
@@ -234,9 +246,7 @@ export function beforeUserSignedIn(
  * Handles an event that is triggered before an email is sent to a user.
  * @param handler - Event handler that is run before an email is sent to a user.
  */
-export function beforeEmailSent(
-  handler: (event: AuthBlockingEvent) => MaybeAsync<BeforeEmailResponse | void>
-): BlockingFunction;
+export function beforeEmailSent(handler: BeforeEmailSentHandler): BlockingFunction;
 
 /**
  * Handles an event that is triggered before an email is sent to a user.
@@ -245,7 +255,7 @@ export function beforeEmailSent(
  */
 export function beforeEmailSent(
   opts: Omit<BlockingOptions, "idToken" | "accessToken" | "refreshToken">,
-  handler: (event: AuthBlockingEvent) => MaybeAsync<BeforeEmailResponse | void>
+  handler: BeforeEmailSentHandler
 ): BlockingFunction;
 
 /**
@@ -256,8 +266,8 @@ export function beforeEmailSent(
 export function beforeEmailSent(
   optsOrHandler:
     | Omit<BlockingOptions, "idToken" | "accessToken" | "refreshToken">
-    | ((event: AuthBlockingEvent) => MaybeAsync<BeforeEmailResponse | void>),
-  handler?: (event: AuthBlockingEvent) => MaybeAsync<BeforeEmailResponse | void>
+    | BeforeEmailSentHandler,
+  handler?: BeforeEmailSentHandler
 ): BlockingFunction {
   return beforeOperation("beforeSendEmail", optsOrHandler, handler);
 }
@@ -265,9 +275,7 @@ export function beforeEmailSent(
  * Handles an event that is triggered before an SMS is sent to a user.
  * @param handler - Event handler that is run before an SMS is sent to a user.
  */
-export function beforeSmsSent(
-  handler: (event: AuthBlockingEvent) => MaybeAsync<BeforeSmsResponse | void>
-): BlockingFunction;
+export function beforeSmsSent(handler: BeforeSmsSentHandler): BlockingFunction;
 
 /**
  * Handles an event that is triggered before an SMS is sent to a user.
@@ -276,7 +284,7 @@ export function beforeSmsSent(
  */
 export function beforeSmsSent(
   opts: Omit<BlockingOptions, "idToken" | "accessToken" | "refreshToken">,
-  handler: (event: AuthBlockingEvent) => MaybeAsync<BeforeSmsResponse | void>
+  handler: BeforeSmsSentHandler
 ): BlockingFunction;
 
 /**
@@ -287,8 +295,8 @@ export function beforeSmsSent(
 export function beforeSmsSent(
   optsOrHandler:
     | Omit<BlockingOptions, "idToken" | "accessToken" | "refreshToken">
-    | ((event: AuthBlockingEvent) => MaybeAsync<BeforeSmsResponse | void>),
-  handler?: (event: AuthBlockingEvent) => MaybeAsync<BeforeSmsResponse | void>
+    | BeforeSmsSentHandler,
+  handler?: BeforeSmsSentHandler
 ): BlockingFunction {
   return beforeOperation("beforeSendSms", optsOrHandler, handler);
 }
diff --git a/src/v2/providers/pubsub.ts b/src/v2/providers/pubsub.ts
index bb151877b..8570fbdaa 100644
--- a/src/v2/providers/pubsub.ts
+++ b/src/v2/providers/pubsub.ts
@@ -265,6 +265,16 @@ export interface PubSubOptions extends options.EventHandlerOptions {
   retry?: boolean | Expression<boolean> | ResetValue;
 }
 
+/** Handler used by {@link onMessagePublished}. */
+export type OnMessagePublishedHandler<T = any> = (
+  event: CloudEvent<MessagePublishedData<T>>
+) => any | Promise<any>;
+
+/** Handler used by {@link onMessagePublished} when accessing v1-compatible fields. */
+export type OnMessagePublishedHandlerWithContext<T = any> = (
+  event: CloudEvent<MessagePublishedData<T>> & V1Compat<"message", V1PubSubMessage<T>>
+) => any | Promise<any>;
+
 /**
  * Handle a message being published to a Pub/Sub topic.
  * @param topic - The Pub/Sub topic to watch for message events.
@@ -273,9 +283,7 @@ export interface PubSubOptions extends options.EventHandlerOptions {
  */
 export function onMessagePublished<T = any>(
   topic: string,
-  handler: (
-    event: CloudEvent<MessagePublishedData<T>> & V1Compat<"message", V1PubSubMessage<T>>
-  ) => any | Promise<any>
+  handler: OnMessagePublishedHandlerWithContext<T>
 ): CloudFunction<CloudEvent<MessagePublishedData<T>>>;
 
 /**
@@ -286,7 +294,7 @@ export function onMessagePublished<T = any>(
  */
 export function onMessagePublished<T = any>(
   topic: string,
-  handler: (event: CloudEvent<MessagePublishedData<T>>) => any | Promise<any>
+  handler: OnMessagePublishedHandler<T>
 ): CloudFunction<CloudEvent<MessagePublishedData<T>>>;
 
 /**
@@ -297,9 +305,7 @@ export function onMessagePublished<T = any>(
  */
 export function onMessagePublished<T = any>(
   options: PubSubOptions,
-  handler: (
-    event: CloudEvent<MessagePublishedData<T>> & V1Compat<"message", V1PubSubMessage<T>>
-  ) => any | Promise<any>
+  handler: OnMessagePublishedHandlerWithContext<T>
 ): CloudFunction<CloudEvent<MessagePublishedData<T>>>;
 
 /**
@@ -310,7 +316,7 @@ export function onMessagePublished<T = any>(
  */
 export function onMessagePublished<T = any>(
   options: PubSubOptions,
-  handler: (event: CloudEvent<MessagePublishedData<T>>) => any | Promise<any>
+  handler: OnMessagePublishedHandler<T>
 ): CloudFunction<CloudEvent<MessagePublishedData<T>>>;
 
 /**
@@ -321,9 +327,7 @@ export function onMessagePublished<T = any>(
  */
 export function onMessagePublished<T = any>(
   topicOrOptions: string | PubSubOptions,
-  handler: (
-    event: CloudEvent<MessagePublishedData<T>> & V1Compat<"message", V1PubSubMessage<T>>
-  ) => any | Promise<any>
+  handler: OnMessagePublishedHandlerWithContext<T>
 ): CloudFunction<CloudEvent<MessagePublishedData<T>>> {
   let topic: string;
   let opts: options.EventHandlerOptions;
diff --git a/src/v2/providers/remoteConfig.ts b/src/v2/providers/remoteConfig.ts
index 7f9ffba22..807d62634 100644
--- a/src/v2/providers/remoteConfig.ts
+++ b/src/v2/providers/remoteConfig.ts
@@ -25,7 +25,7 @@ import { initV2Endpoint, ManifestEndpoint } from "../../runtime/manifest";
 import { CloudEvent, CloudFunction } from "../core";
 import { EventHandlerOptions, getGlobalOptions, optionsToEndpoint } from "../options";
 import { wrapTraceContext } from "../trace";
-import { V1Compat, addV1Compat } from "../compat";
+import { addV1Compat, V1Compat } from "../compat";
 
 /** @internal */
 export const eventType = "google.firebase.remoteconfig.remoteConfig.v1.updated";
@@ -88,6 +88,14 @@ export interface ConfigUpdateData {
   rollbackSource: number;
 }
 
+/** Handler used by {@link onConfigUpdated}. */
+export type OnConfigUpdatedHandler = (event: CloudEvent<ConfigUpdateData>) => any | Promise<any>;
+
+/** Handler used by {@link onConfigUpdated} when accessing v1-compatible fields. */
+export type OnConfigUpdatedHandlerWithContext = (
+  event: CloudEvent<ConfigUpdateData> & V1Compat<"version", ConfigUpdateData>
+) => any | Promise<any>;
+
 /**
  * Event handler which triggers when data is updated in a Remote Config.
  *
@@ -95,9 +103,7 @@ export interface ConfigUpdateData {
  * @returns A function that you can export and deploy.
  */
 export function onConfigUpdated(
-  handler: (
-    event: CloudEvent<ConfigUpdateData> & V1Compat<"version", ConfigUpdateData>
-  ) => any | Promise<any>
+  handler: OnConfigUpdatedHandlerWithContext
 ): CloudFunction<CloudEvent<ConfigUpdateData>>;
 
 /**
@@ -107,7 +113,7 @@ export function onConfigUpdated(
  * @returns A function that you can export and deploy.
  */
 export function onConfigUpdated(
-  handler: (event: CloudEvent<ConfigUpdateData>) => any | Promise<any>
+  handler: OnConfigUpdatedHandler
 ): CloudFunction<CloudEvent<ConfigUpdateData>>;
 
 /**
@@ -119,9 +125,7 @@ export function onConfigUpdated(
  */
 export function onConfigUpdated(
   opts: EventHandlerOptions,
-  handler: (
-    event: CloudEvent<ConfigUpdateData> & V1Compat<"version", ConfigUpdateData>
-  ) => any | Promise<any>
+  handler: OnConfigUpdatedHandlerWithContext
 ): CloudFunction<CloudEvent<ConfigUpdateData>>;
 
 /**
@@ -133,7 +137,7 @@ export function onConfigUpdated(
  */
 export function onConfigUpdated(
   opts: EventHandlerOptions,
-  handler: (event: CloudEvent<ConfigUpdateData>) => any | Promise<any>
+  handler: OnConfigUpdatedHandler
 ): CloudFunction<CloudEvent<ConfigUpdateData>>;
 
 /**
diff --git a/src/v2/providers/scheduler.ts b/src/v2/providers/scheduler.ts
index 876ff7194..7604cc573 100644
--- a/src/v2/providers/scheduler.ts
+++ b/src/v2/providers/scheduler.ts
@@ -128,6 +128,14 @@ export interface ScheduleOptions extends options.GlobalOptions {
   maxDoublings?: number | Expression<number> | ResetValue;
 }
 
+/** Handler used by {@link onSchedule}. */
+export type OnScheduleHandler = (event: ScheduledEvent) => void | Promise<void>;
+
+/** Handler used by {@link onSchedule} when accessing v1-compatible context. */
+export type OnScheduleHandlerWithContext = (
+  event: ScheduledEvent & { context: EventContext }
+) => void | Promise<void>;
+
 /**
  * Handler for scheduled functions. Triggered whenever the associated
  * scheduler job sends a http request.
@@ -137,7 +145,7 @@ export interface ScheduleOptions extends options.GlobalOptions {
  */
 export function onSchedule(
   schedule: string,
-  handler: (event: ScheduledEvent & { context: EventContext }) => void | Promise<void>
+  handler: OnScheduleHandlerWithContext
 ): ScheduleFunction;
 
 /**
@@ -147,10 +155,7 @@ export function onSchedule(
  * @param handler - A function to execute when triggered.
  * @returns A function that you can export and deploy.
  */
-export function onSchedule(
-  schedule: string,
-  handler: (event: ScheduledEvent) => void | Promise<void>
-): ScheduleFunction;
+export function onSchedule(schedule: string, handler: OnScheduleHandler): ScheduleFunction;
 
 /**
  * Handler for scheduled functions. Triggered whenever the associated
@@ -161,7 +166,7 @@ export function onSchedule(
  */
 export function onSchedule(
   options: ScheduleOptions,
-  handler: (event: ScheduledEvent & { context: EventContext }) => void | Promise<void>
+  handler: OnScheduleHandlerWithContext
 ): ScheduleFunction;
 
 /**
@@ -171,10 +176,7 @@ export function onSchedule(
  * @param handler - A function to execute when triggered.
  * @returns A function that you can export and deploy.
  */
-export function onSchedule(
-  options: ScheduleOptions,
-  handler: (event: ScheduledEvent) => void | Promise<void>
-): ScheduleFunction;
+export function onSchedule(options: ScheduleOptions, handler: OnScheduleHandler): ScheduleFunction;
 
 /**
  * Handler for scheduled functions. Triggered whenever the associated
@@ -185,7 +187,7 @@ export function onSchedule(
  */
 export function onSchedule(
   args: string | ScheduleOptions,
-  handler: (event: any) => void | Promise<void>
+  handler: OnScheduleHandlerWithContext
 ): ScheduleFunction {
   const separatedOpts = getOpts(args);
 
@@ -213,7 +215,7 @@ export function onSchedule(
     });
 
     try {
-      await handler(event);
+      await handler(event as ScheduledEvent & { context: EventContext });
       res.status(200).send();
     } catch (err) {
       logger.error((err as Error).message);
diff --git a/src/v2/providers/storage.ts b/src/v2/providers/storage.ts
index 3e705f243..aeb74fed6 100644
--- a/src/v2/providers/storage.ts
+++ b/src/v2/providers/storage.ts
@@ -304,6 +304,38 @@ export interface StorageOptions extends options.EventHandlerOptions {
   retry?: boolean | Expression<boolean> | ResetValue;
 }
 
+/** Handler used by Cloud Storage event triggers. */
+export type StorageEventHandler = (event: StorageEvent) => any | Promise<any>;
+
+/** Handler used by Cloud Storage event triggers when accessing v1-compatible fields. */
+export type StorageEventHandlerWithContext = (
+  event: StorageEvent & V1Compat<"object", StorageObjectData>
+) => any | Promise<any>;
+
+/** Handler used by {@link onObjectArchived}. */
+export type OnObjectArchivedHandler = StorageEventHandler;
+
+/** Handler used by {@link onObjectArchived} when accessing v1-compatible fields. */
+export type OnObjectArchivedHandlerWithContext = StorageEventHandlerWithContext;
+
+/** Handler used by {@link onObjectFinalized}. */
+export type OnObjectFinalizedHandler = StorageEventHandler;
+
+/** Handler used by {@link onObjectFinalized} when accessing v1-compatible fields. */
+export type OnObjectFinalizedHandlerWithContext = StorageEventHandlerWithContext;
+
+/** Handler used by {@link onObjectDeleted}. */
+export type OnObjectDeletedHandler = StorageEventHandler;
+
+/** Handler used by {@link onObjectDeleted} when accessing v1-compatible fields. */
+export type OnObjectDeletedHandlerWithContext = StorageEventHandlerWithContext;
+
+/** Handler used by {@link onObjectMetadataUpdated}. */
+export type OnObjectMetadataUpdatedHandler = StorageEventHandler;
+
+/** Handler used by {@link onObjectMetadataUpdated} when accessing v1-compatible fields. */
+export type OnObjectMetadataUpdatedHandlerWithContext = StorageEventHandlerWithContext;
+
 /**
  * Event handler sent only when a bucket has enabled object versioning.
  * This event indicates that the live version of an object has become an
@@ -313,7 +345,7 @@ export interface StorageOptions extends options.EventHandlerOptions {
  * @param handler - Event handler which is run every time a Google Cloud Storage archival occurs.
  */
 export function onObjectArchived(
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+  handler: OnObjectArchivedHandlerWithContext
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -324,9 +356,7 @@ export function onObjectArchived(
  *
  * @param handler - Event handler which is run every time a Google Cloud Storage archival occurs.
  */
-export function onObjectArchived(
-  handler: (event: StorageEvent) => any | Promise<any>
-): CloudFunction<StorageEvent>;
+export function onObjectArchived(handler: OnObjectArchivedHandler): CloudFunction<StorageEvent>;
 
 /**
  * Event handler sent only when a bucket has enabled object versioning.
@@ -339,7 +369,7 @@ export function onObjectArchived(
  */
 export function onObjectArchived(
   bucket: string | Expression<string>,
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+  handler: OnObjectArchivedHandlerWithContext
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -353,7 +383,7 @@ export function onObjectArchived(
  */
 export function onObjectArchived(
   bucket: string | Expression<string>,
-  handler: (event: StorageEvent) => any | Promise<any>
+  handler: OnObjectArchivedHandler
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -367,7 +397,7 @@ export function onObjectArchived(
  */
 export function onObjectArchived(
   opts: StorageOptions,
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+  handler: OnObjectArchivedHandlerWithContext
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -381,7 +411,7 @@ export function onObjectArchived(
  */
 export function onObjectArchived(
   opts: StorageOptions,
-  handler: (event: StorageEvent) => any | Promise<any>
+  handler: OnObjectArchivedHandler
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -415,7 +445,7 @@ export function onObjectArchived(
  * @param handler - Event handler which is run every time a Google Cloud Storage object creation occurs.
  */
 export function onObjectFinalized(
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+  handler: OnObjectFinalizedHandlerWithContext
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -428,9 +458,7 @@ export function onObjectFinalized(
  *
  * @param handler - Event handler which is run every time a Google Cloud Storage object creation occurs.
  */
-export function onObjectFinalized(
-  handler: (event: StorageEvent) => any | Promise<any>
-): CloudFunction<StorageEvent>;
+export function onObjectFinalized(handler: OnObjectFinalizedHandler): CloudFunction<StorageEvent>;
 
 /**
  * Event handler which fires every time a Google Cloud Storage object
@@ -445,7 +473,7 @@ export function onObjectFinalized(
  */
 export function onObjectFinalized(
   bucket: string | Expression<string>,
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+  handler: OnObjectFinalizedHandlerWithContext
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -461,7 +489,7 @@ export function onObjectFinalized(
  */
 export function onObjectFinalized(
   bucket: string | Expression<string>,
-  handler: (event: StorageEvent) => any | Promise<any>
+  handler: OnObjectFinalizedHandler
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -477,7 +505,7 @@ export function onObjectFinalized(
  */
 export function onObjectFinalized(
   opts: StorageOptions,
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+  handler: OnObjectFinalizedHandlerWithContext
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -493,7 +521,7 @@ export function onObjectFinalized(
  */
 export function onObjectFinalized(
   opts: StorageOptions,
-  handler: (event: StorageEvent) => any | Promise<any>
+  handler: OnObjectFinalizedHandler
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -530,7 +558,7 @@ export function onObjectFinalized(
  * @param handler - Event handler which is run every time a Google Cloud Storage object deletion occurs.
  */
 export function onObjectDeleted(
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+  handler: OnObjectDeletedHandlerWithContext
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -544,9 +572,7 @@ export function onObjectDeleted(
  *
  * @param handler - Event handler which is run every time a Google Cloud Storage object deletion occurs.
  */
-export function onObjectDeleted(
-  handler: (event: StorageEvent) => any | Promise<any>
-): CloudFunction<StorageEvent>;
+export function onObjectDeleted(handler: OnObjectDeletedHandler): CloudFunction<StorageEvent>;
 
 /**
  * Event handler which fires every time a Google Cloud Storage deletion occurs.
@@ -562,7 +588,7 @@ export function onObjectDeleted(
  */
 export function onObjectDeleted(
   bucket: string | Expression<string>,
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+  handler: OnObjectDeletedHandlerWithContext
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -579,7 +605,7 @@ export function onObjectDeleted(
  */
 export function onObjectDeleted(
   bucket: string | Expression<string>,
-  handler: (event: StorageEvent) => any | Promise<any>
+  handler: OnObjectDeletedHandler
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -596,7 +622,7 @@ export function onObjectDeleted(
  */
 export function onObjectDeleted(
   opts: StorageOptions,
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+  handler: OnObjectDeletedHandlerWithContext
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -613,7 +639,7 @@ export function onObjectDeleted(
  */
 export function onObjectDeleted(
   opts: StorageOptions,
-  handler: (event: StorageEvent) => any | Promise<any>
+  handler: OnObjectDeletedHandler
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -647,7 +673,7 @@ export function onObjectDeleted(
  * @param handler - Event handler which is run every time a Google Cloud Storage object metadata update occurs.
  */
 export function onObjectMetadataUpdated(
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+  handler: OnObjectMetadataUpdatedHandlerWithContext
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -658,7 +684,7 @@ export function onObjectMetadataUpdated(
  * @param handler - Event handler which is run every time a Google Cloud Storage object metadata update occurs.
  */
 export function onObjectMetadataUpdated(
-  handler: (event: StorageEvent) => any | Promise<any>
+  handler: OnObjectMetadataUpdatedHandler
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -670,7 +696,7 @@ export function onObjectMetadataUpdated(
  */
 export function onObjectMetadataUpdated(
   bucket: string | Expression<string>,
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+  handler: OnObjectMetadataUpdatedHandlerWithContext
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -682,7 +708,7 @@ export function onObjectMetadataUpdated(
  */
 export function onObjectMetadataUpdated(
   bucket: string | Expression<string>,
-  handler: (event: StorageEvent) => any | Promise<any>
+  handler: OnObjectMetadataUpdatedHandler
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -694,7 +720,7 @@ export function onObjectMetadataUpdated(
  */
 export function onObjectMetadataUpdated(
   opts: StorageOptions,
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+  handler: OnObjectMetadataUpdatedHandlerWithContext
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -706,7 +732,7 @@ export function onObjectMetadataUpdated(
  */
 export function onObjectMetadataUpdated(
   opts: StorageOptions,
-  handler: (event: StorageEvent) => any | Promise<any>
+  handler: OnObjectMetadataUpdatedHandler
 ): CloudFunction<StorageEvent>;
 
 /**
@@ -734,8 +760,8 @@ export function onOperation(
     | string
     | Expression<string>
     | StorageOptions
-    | ((event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>),
-  handler: (event: StorageEvent & V1Compat<"object", StorageObjectData>) => any | Promise<any>
+    | StorageEventHandlerWithContext,
+  handler: StorageEventHandlerWithContext
 ): CloudFunction<StorageEvent> {
   if (typeof bucketOrOptsOrHandler === "function") {
     handler = bucketOrOptsOrHandler as (event: any) => any | Promise<any>;
diff --git a/src/v2/providers/tasks.ts b/src/v2/providers/tasks.ts
index 9bb0cb13f..50fea7168 100644
--- a/src/v2/providers/tasks.ts
+++ b/src/v2/providers/tasks.ts
@@ -176,6 +176,14 @@ export interface TaskQueueFunction<T = any> extends HttpsFunction {
   run(request: Request<T>): void | Promise<void>;
 }
 
+/** Handler used by {@link onTaskDispatched}. */
+export type OnTaskDispatchedHandler<Args = any> = (request: Request<Args>) => void | Promise<void>;
+
+/** Handler used by {@link onTaskDispatched} when accessing v1-compatible context. */
+export type OnTaskDispatchedHandlerWithContext<Args = any> = (
+  request: Request<Args> & { context: TaskContext }
+) => void | Promise<void>;
+
 /**
  * Creates a handler for tasks sent to a Google Cloud Tasks queue.
  * @param handler - A callback to handle task requests.
@@ -183,7 +191,7 @@ export interface TaskQueueFunction<T = any> extends HttpsFunction {
  * @returns A function you can export and deploy.
  */
 export function onTaskDispatched<Args = any>(
-  handler: (request: Request<Args> & { context: TaskContext }) => void | Promise<void>
+  handler: OnTaskDispatchedHandlerWithContext<Args>
 ): TaskQueueFunction<Args>;
 
 /**
@@ -193,7 +201,7 @@ export function onTaskDispatched<Args = any>(
  * @returns A function you can export and deploy.
  */
 export function onTaskDispatched<Args = any>(
-  handler: (request: Request<Args>) => void | Promise<void>
+  handler: OnTaskDispatchedHandler<Args>
 ): TaskQueueFunction<Args>;
 
 /**
@@ -205,7 +213,7 @@ export function onTaskDispatched<Args = any>(
  */
 export function onTaskDispatched<Args = any>(
   options: TaskQueueOptions,
-  handler: (request: Request<Args> & { context: TaskContext }) => void | Promise<void>
+  handler: OnTaskDispatchedHandlerWithContext<Args>
 ): TaskQueueFunction<Args>;
 
 /**
@@ -217,7 +225,7 @@ export function onTaskDispatched<Args = any>(
  */
 export function onTaskDispatched<Args = any>(
   options: TaskQueueOptions,
-  handler: (request: Request<Args>) => void | Promise<void>
+  handler: OnTaskDispatchedHandler<Args>
 ): TaskQueueFunction<Args>;
 export function onTaskDispatched<Args = any>(
   optsOrHandler: TaskQueueOptions | ((request: any) => void | Promise<void>),
diff --git a/src/v2/providers/testLab.ts b/src/v2/providers/testLab.ts
index 3b4e5a3c1..47815ae4e 100644
--- a/src/v2/providers/testLab.ts
+++ b/src/v2/providers/testLab.ts
@@ -144,6 +144,11 @@ export interface TestMatrixCompletedData {
   testMatrixId: string;
 }
 
+/** Handler used by {@link onTestMatrixCompleted}. */
+export type OnTestMatrixCompletedHandler = (
+  event: CloudEvent<TestMatrixCompletedData>
+) => any | Promise<any>;
+
 /**
  * Event handler which triggers when a Firebase test matrix completes.
  *
@@ -152,7 +157,7 @@ export interface TestMatrixCompletedData {
  * @alpha
  */
 export function onTestMatrixCompleted(
-  handler: (event: CloudEvent<TestMatrixCompletedData>) => any | Promise<any>
+  handler: OnTestMatrixCompletedHandler
 ): CloudFunction<CloudEvent<TestMatrixCompletedData>>;
 
 /**
@@ -165,7 +170,7 @@ export function onTestMatrixCompleted(
  */
 export function onTestMatrixCompleted(
   opts: EventHandlerOptions,
-  handler: (event: CloudEvent<TestMatrixCompletedData>) => any | Promise<any>
+  handler: OnTestMatrixCompletedHandler
 ): CloudFunction<CloudEvent<TestMatrixCompletedData>>;
 
 /**
@@ -177,10 +182,8 @@ export function onTestMatrixCompleted(
  * @alpha
  */
 export function onTestMatrixCompleted(
-  optsOrHandler:
-    | EventHandlerOptions
-    | ((event: CloudEvent<TestMatrixCompletedData>) => any | Promise<any>),
-  handler?: (event: CloudEvent<TestMatrixCompletedData>) => any | Promise<any>
+  optsOrHandler: EventHandlerOptions | OnTestMatrixCompletedHandler,
+  handler?: OnTestMatrixCompletedHandler
 ): CloudFunction<CloudEvent<TestMatrixCompletedData>> {
   if (typeof optsOrHandler === "function") {
     handler = optsOrHandler as (event: CloudEvent<TestMatrixCompletedData>) => any | Promise<any>;