diff --git a/java-bigquery/google-cloud-bigquery-jdbc/.gitignore b/java-bigquery/google-cloud-bigquery-jdbc/.gitignore
index 2c4fba513e11..52e30f1bcd64 100644
--- a/java-bigquery/google-cloud-bigquery-jdbc/.gitignore
+++ b/java-bigquery/google-cloud-bigquery-jdbc/.gitignore
@@ -4,4 +4,6 @@ target-it/**
 **/ITBigQueryJDBCLocalTest.java
 
 tools/**/*.class
+tools/**/drivers/**
+tools/**/logs/**
 tools/**/*.jfr
\ No newline at end of file
diff --git a/java-bigquery/google-cloud-bigquery-jdbc/tools/client/Makefile b/java-bigquery/google-cloud-bigquery-jdbc/tools/client/Makefile
index 72e7cf928bb8..16460397b1ad 100644
--- a/java-bigquery/google-cloud-bigquery-jdbc/tools/client/Makefile
+++ b/java-bigquery/google-cloud-bigquery-jdbc/tools/client/Makefile
@@ -21,6 +21,12 @@ DRIVER_CLASS = com.google.cloud.bigquery.jdbc.BigQueryDriver
 URL ?= jdbc:bigquery://https://www.googleapis.com/bigquery/v2:443;
 CREDENTIALS ?= $(GOOGLE_APPLICATION_CREDENTIALS)
 
+# Default connection parameters
+PARAMS = ProjectId=bigquery-devtools-drivers;OAuthType=0;OAuthServiceAcctEmail=;OAuthPvtKeyPath=$(CREDENTIALS);
+
+# Additional connection parameters
+EXTRA_PARAMS ?=
+
 ROWS ?= 10
 COLS ?= 5
 METHOD ?= getTables
@@ -42,18 +48,9 @@ else
   JFR_FLAGS =
 endif
 
-COMMON_FLAGS = --url "$(URL)" \
+COMMON_FLAGS = --url "$(URL);$(DEFAULT_PARAMS);$(PARAMS);$(EXTRA_PARAMS)" \
                --driver-jar "$(DRIVER_JAR)" \
-               --driver-class "$(DRIVER_CLASS)" \
-               --ProjectId "bigquery-devtools-drivers" \
-               --OAuthType=0 \
-               --OAuthServiceAcctEmail="" \
-               --OAuthPvtKeyPath="$(CREDENTIALS)" \
-               --EnableHighThroughputAPI=1 \
-               --HighThroughputActivationRatio=0 \
-               --HighThroughputMinTableSize=0 \
-               --MaxResults=20000 \
-               --EnableSession=1
+               --driver-class "$(DRIVER_CLASS)"
 
 query: classes
 	$(J) $(JFR_FLAGS) -cp .:$(DRIVER_JAR) JDBCClient --action query $(COMMON_FLAGS) --query "$(QUERY)" $(OUTPUT_FLAG) $(EXTRA_ARGS)
diff --git a/java-bigquery/google-cloud-bigquery-jdbc/tools/client/README.md b/java-bigquery/google-cloud-bigquery-jdbc/tools/client/README.md
index a3d396acfe6d..c422a2c968d2 100644
--- a/java-bigquery/google-cloud-bigquery-jdbc/tools/client/README.md
+++ b/java-bigquery/google-cloud-bigquery-jdbc/tools/client/README.md
@@ -19,6 +19,8 @@ The Makefile provides convenient targets to run the client. You can override def
 Common variables:
 - `URL`: JDBC connection URL (defaults to public BigQuery endpoint)
 - `CREDENTIALS`: Path to service account JSON key (defaults to `$GOOGLE_APPLICATION_CREDENTIALS`)
+- `PARAMS`: Default set of connection string params.
+- `EXTRA_PARAMS`: Additional connection string parameters (e.g., `EXTRA_PARAMS="Timeout=30;LogLevel=6;"`)
 - `OUTPUT`: Set to `false` to suppress query result output (defaults to `true`)
 - `EXTRA_ARGS`: Extra arguments to pass to the client (e.g., `EXTRA_ARGS="--table my_table"`)