fix: #3036 parameter filtering for CrewAI functions with **kwargs

Merge https://github.com/google/adk-python/pull/3037

fix: [#3036](https://github.com/google/adk-python/issues/3036)

- Fix FunctionTool parameter filtering to support CrewAI-style tools
- Functions with **kwargs now receive all parameters except 'self' and 'tool_context'
- Maintains backward compatibility with explicit parameter functions
- Add comprehensive tests for **kwargs functionality

Fixes parameter filtering issue where CrewAI tools using **kwargs pattern would receive empty parameter dictionaries, causing search_query and other parameters to be None.

#non-breaking

COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/3037 from omarcevi:fix/function-tool-kwargs-parameter-filtering 012bbfcfd68e83a29635ac74718a1bd1323c5187
PiperOrigin-RevId: 825275686

tests/unittests/tools/test_function_tool.py

@@ -22,6 +22,15 @@ from google.adk.tools.tool_context import ToolContext
 import pytest
 
 
+@pytest.fixture
+def mock_tool_context() -> ToolContext:
+  """Fixture that provides a mock ToolContext for testing."""
+  mock_invocation_context = MagicMock(spec=InvocationContext)
+  mock_invocation_context.session = MagicMock(spec=Session)
+  mock_invocation_context.session.state = MagicMock()
+  return ToolContext(invocation_context=mock_invocation_context)
+
+
 def function_for_testing_with_no_args():
   """Function for testing with no args."""
   pass
@@ -394,3 +403,28 @@ async def test_run_async_with_require_confirmation():
       tool_context=tool_context_mock,
   )
   assert result == {"received_arg": "hello"}
+
+
+@pytest.mark.asyncio
+async def test_run_async_parameter_filtering(mock_tool_context):
+  """Test that parameter filtering works correctly for functions with explicit parameters."""
+
+  def explicit_params_func(arg1: str, arg2: int):
+    """Function with explicit parameters (no **kwargs)."""
+    return {"arg1": arg1, "arg2": arg2}
+
+  tool = FunctionTool(explicit_params_func)
+
+  # Test that unexpected parameters are still filtered out for non-kwargs functions
+  result = await tool.run_async(
+      args={
+          "arg1": "test",
+          "arg2": 42,
+          "unexpected_param": "should_be_filtered",
+      },
+      tool_context=mock_tool_context,
+  )
+
+  assert result == {"arg1": "test", "arg2": 42}
+  # Explicitly verify that unexpected_param was filtered out and not passed to the function
+  assert "unexpected_param" not in result