Class FunctionTool

src/google/adk/tools/function_tool.py:42–351

A tool that wraps a user-defined Python function. Attributes: func: The function to wrap.

class FunctionTool(BaseTool):
  """A tool that wraps a user-defined Python function.

  Attributes:
    func: The function to wrap.
  """

  def __init__(
      self,
      func: Callable[..., Any],
      *,
      require_confirmation: Union[bool, Callable[..., bool]] = False,
  ):
    """Initializes the FunctionTool. Extracts metadata from a callable object.

    Args:
      func: The function to wrap.
      require_confirmation: Whether this tool requires confirmation. A boolean or
        a callable that takes the function's arguments and returns a boolean. If
        the callable returns True, the tool will require confirmation from the
        user.
    """
    name = ''
    doc = ''
    # Handle different types of callables
    if hasattr(func, '__name__'):
      # Regular functions, unbound methods, etc.
      name = func.__name__
    elif hasattr(func, '__class__'):
      # Callable objects, bound methods, etc.
      name = func.__class__.__name__

    # Get documentation (prioritize direct __doc__ if available)
    if hasattr(func, '__doc__') and func.__doc__:
      doc = inspect.cleandoc(func.__doc__)
    elif (
        hasattr(func, '__call__')
        and hasattr(func.__call__, '__doc__')
        and func.__call__.__doc__
    ):
      # For callable objects, try to get docstring from __call__ method
      doc = inspect.cleandoc(func.__call__.__doc__)

    super().__init__(name=name, description=doc)
    self.func = func
    # Detect context parameter by type annotation, fallback to 'tool_context' name
    self._context_param_name = find_context_parameter(func) or 'tool_context'
    self._ignore_params = [self._context_param_name, 'input_stream']
    self._require_confirmation = require_confirmation

  @override
  def _get_declaration(self) -> Optional[types.FunctionDeclaration]:
    function_decl = types.FunctionDeclaration.model_validate(
        build_function_declaration(
            func=self.func,
            # The model doesn't understand the function context.
            # input_stream is for streaming tool
            ignore_params=self._ignore_params,