tighten comment and add test for raw dict schema

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: harche

src/google/adk/tools/set_model_response_tool.py

@@ -88,9 +88,7 @@ def set_model_response() -> str:
           )
       ]
     elif isinstance(output_schema, dict):
-      # Raw dict schema instance — use `dict` type as annotation, not the
-      # instance itself, because dict instances are unhashable and break
-      # _is_builtin_primitive_or_compound's `annotation in ...` check.
+      # Use `dict` type, not the instance — dict instances are unhashable.
       params = [
           inspect.Parameter(
               'response',

tests/unittests/tools/test_set_model_response_tool.py

@@ -467,3 +467,18 @@ async def test_run_async_dict_schema():
   assert result is not None
   assert isinstance(result, dict)
   assert result == {'a': 1, 'b': 2, 'c': 3}
+
+
+def test_tool_initialization_raw_dict_instance():
+  """Test tool initialization with a raw dict schema instance."""
+  raw_schema = {'type': 'object', 'properties': {'name': {'type': 'string'}}}
+  tool = SetModelResponseTool(raw_schema)
+
+  assert tool.output_schema == raw_schema
+  assert not tool._is_basemodel
+  assert not tool._is_list_of_basemodel
+
+  sig = inspect.signature(tool.func)
+  assert 'response' in sig.parameters
+  assert len(sig.parameters) == 1
+  assert sig.parameters['response'].annotation is dict