fix: pass tool context into require_confirmation function in McpTool

Aligns with the FunctionTool implementation of require_confirmation. This fixes https://github.com/google/adk-python/issues/4327.

Co-authored-by: Kathy Wu <wukathy@google.com>
PiperOrigin-RevId: 865566362

src/google/adk/tools/mcp_tool/mcp_tool.py

@@ -151,8 +151,31 @@ class McpTool(BaseAuthenticatedTool):
       self, *, args: dict[str, Any], tool_context: ToolContext
   ) -> Any:
     if isinstance(self._require_confirmation, Callable):
+      args_to_call = args.copy()
+      try:
+        signature = inspect.signature(self._require_confirmation)
+        valid_params = set(signature.parameters.keys())
+        has_kwargs = any(
+            param.kind == inspect.Parameter.VAR_KEYWORD
+            for param in signature.parameters.values()
+        )
+
+        if "tool_context" in valid_params or has_kwargs:
+          args_to_call["tool_context"] = tool_context
+
+        # Filter args_to_call only if there's no **kwargs
+        if not has_kwargs:
+          # Add tool_context to valid_params if it was added to args_to_call
+          if "tool_context" in args_to_call:
+            valid_params.add("tool_context")
+          args_to_call = {
+              k: v for k, v in args_to_call.items() if k in valid_params
+          }
+      except ValueError:
+        args_to_call = args
+
       require_confirmation = await self._invoke_callable(
-          self._require_confirmation, args
+          self._require_confirmation, args_to_call
       )
     else:
       require_confirmation = bool(self._require_confirmation)

tests/unittests/tools/mcp_tool/test_mcp_tool.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import inspect
 from unittest.mock import AsyncMock
 from unittest.mock import Mock
 from unittest.mock import patch
@@ -669,6 +670,50 @@ class TestMCPTool:
           args=args, tool_context=tool_context
       )
 
+  @pytest.mark.asyncio
+  async def test_run_async_require_confirmation_callable_with_arg_filtering(
+      self,
+  ):
+    """Test require_confirmation=callable with argument filtering."""
+
+    async def _require_confirmation_func(
+        param1: str, tool_context: ToolContext
+    ):
+      return True
+
+    tool = MCPTool(
+        mcp_tool=self.mock_mcp_tool,
+        mcp_session_manager=self.mock_session_manager,
+        require_confirmation=_require_confirmation_func,
+    )
+    tool_context = Mock(spec=ToolContext)
+    tool_context.tool_confirmation = None
+    tool_context.request_confirmation = Mock()
+    args = {"param1": "test_value", "extra_arg": 123}
+
+    with patch.object(
+        tool, "_invoke_callable", new_callable=AsyncMock
+    ) as mock_invoke_callable:
+      mock_invoke_callable.return_value = (
+          True  # Mock the return of require_confirmation
+      )
+
+      result = await tool.run_async(args=args, tool_context=tool_context)
+      expected_args_to_call = {
+          "param1": "test_value",
+          "tool_context": tool_context,
+      }
+      mock_invoke_callable.assert_called_once_with(
+          _require_confirmation_func, expected_args_to_call
+      )
+
+      assert result == {
+          "error": (
+              "This tool call requires confirmation, please approve or reject."
+          )
+      }
+      tool_context.request_confirmation.assert_called_once()
+
   @pytest.mark.asyncio
   async def test_run_async_require_confirmation_callable_true_no_confirmation(
       self,