def __call__(
      self, tool: BaseTool, readonly_context: Optional[ReadonlyContext] = None
  ) -> bool:
    """Decide whether the passed-in tool should be exposed to LLM based on the

    current context. True if the tool is usable by the LLM.

    It's used to filter tools in the toolset.
    """
Decide whether the passed-in tool should be exposed to LLM based on the

    current context. True if the tool is usable by the LLM.

    It's used to filter tools in the toolset.
    
src/google/adk/tools/base_toolset.py