[tool] fix: remove circular fallback in BaseTool.__init__

[cyyueyang]

What does this PR do?

Remove the or self.get_openai_tool_schema() fallback in
BaseTool.__init__. It creates a circular reference:
get_openai_tool_schema() returns self.tool_schema, but when
tool_schema=None the or calls it before the attribute exists
→ AttributeError.

The fix: tool_schema must be explicitly provided. The existing
assertion catches the None case with a clear error message.

Checklist Before Starting

• Search for similar PRs. Query: base_tool get_openai_tool_schema circular
• Format the PR title as [tool] fix: ...

Test

Not covered by CI; verified locally:

Scenario	Result
BaseTool(config, valid_schema)	works as before
BaseTool(config, None)	AssertionError: Tool schema is not set! (clear, no crash)
Subclass constructs schema in __init__	works correctly
get_openai_tool_schema() as getter after init	works as before

API and Usage Example

No API change. tool_schema must always be provided to __init__.
Subclasses that need to construct their own schema should do it in
__init__ and pass it to super().__init__():

class MyTool(BaseTool):
    def __init__(self, config: dict, tool_schema: OpenAIFunctionToolSchema = None):
        if tool_schema is None:
            tool_schema = OpenAIFunctionToolSchema.model_validate({...})
        super().__init__(config, tool_schema)

Design & Code Changes

1 file: verl/tools/base_tool.py (+1, −1)

  -        self.tool_schema = tool_schema or self.get_openai_tool_schema()
  +        self.tool_schema = tool_schema

Checklist Before Submitting

• Read the Contribute Guide.
• Apply pre-commit checks
• Add / Update the documentation — not needed
• Add unit or end-to-end test(s) — not feasible: latent init bug, existing path always passes tool_schema

[gemini-code-assist]

Code Review

This pull request removes the fallback to get_openai_tool_schema when initializing BaseTool. The reviewer notes that this change breaks subclasses that dynamically define their schema, and suggests setting self.tool_schema first to avoid potential AttributeError circularity before falling back to get_openai_tool_schema.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.

[gemini-code-assist]

Removing the fallback entirely breaks subclasses of BaseTool that override get_openai_tool_schema() to dynamically define their schema in code (which is a common pattern when tool_schema is not provided in the configuration, passing None to __init__).

To resolve the circular reference/AttributeError without breaking subclassing, we can set self.tool_schema = tool_schema first. This ensures the attribute exists (even if it is None), so calling self.get_openai_tool_schema() as a fallback will not raise an AttributeError and will correctly invoke the subclass's overridden method.

Suggested change

	self.tool_schema = tool_schema
	self.tool_schema = tool_schema
	if self.tool_schema is None:
	self.tool_schema = self.get_openai_tool_schema()