From 905c631e1cbddffe19f039e4fb95bb93fb9b9ac7 Mon Sep 17 00:00:00 2001
From: chelsealong <chelsealong@126.com>
Date: Wed, 16 Sep 2026 20:20:14 +0000
Subject: [PATCH] fix(evaluation): disable AFC in LlmAsJudge's default judge
 request config

The judge's default GenerateContentConfig() leaves
automatic_function_calling unset, so google-genai takes the AFC branch
in AsyncModels.generate_content and logs a spurious warning on every
eval run, even though the judge sends no tools and never needs AFC.
Explicitly disabling it removes the warning without changing the
request sent to the model (the field is client-side only).
---
 src/google/adk/evaluation/llm_as_judge.py     |  6 ++-
 .../unittests/evaluation/test_llm_as_judge.py | 53 +++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/src/google/adk/evaluation/llm_as_judge.py b/src/google/adk/evaluation/llm_as_judge.py
index ce484ef58a7..9d6f59c7fb9 100644
--- a/src/google/adk/evaluation/llm_as_judge.py
+++ b/src/google/adk/evaluation/llm_as_judge.py
@@ -222,7 +222,11 @@ async def _evaluate_single_sample_with_sem(
               )
           ],
           config=self._judge_model_options.judge_model_config
-          or genai_types.GenerateContentConfig(),
+          or genai_types.GenerateContentConfig(
+              automatic_function_calling=genai_types.AutomaticFunctionCallingConfig(
+                  disable=True
+              )
+          ),
       )
       add_default_retry_options_if_not_present(llm_request)
       num_samples = self._judge_model_options.num_samples
diff --git a/tests/unittests/evaluation/test_llm_as_judge.py b/tests/unittests/evaluation/test_llm_as_judge.py
index d535febf4c9..f0b98f4065f 100644
--- a/tests/unittests/evaluation/test_llm_as_judge.py
+++ b/tests/unittests/evaluation/test_llm_as_judge.py
@@ -250,6 +250,59 @@ async def test_evaluate_invocations_with_mock(
   assert mock_llm_as_judge.aggregate_invocation_results.call_count == 1
 
 
+@pytest.mark.asyncio
+async def test_evaluate_invocations_default_config_disables_afc(
+    mock_judge_model, mocker
+):
+  # The default judge request must disable google-genai's automatic function
+  # calling, since the judge never calls tools and enabling it only produces
+  # a spurious AFC warning on every eval run.
+  judge = MockLlmAsJudge(
+      eval_metric=EvalMetric(
+          metric_name="test_metric",
+          threshold=0.5,
+          criterion=LlmAsAJudgeCriterion(
+              threshold=0.5,
+              judge_model_options=JudgeModelOptions(
+                  judge_model="gemini-2.5-flash",
+                  num_samples=1,
+              ),
+          ),
+      ),
+      criterion_type=LlmAsAJudgeCriterion,
+  )
+  judge._judge_model = mock_judge_model
+  captured_requests = []
+  original_generate_content_async = mock_judge_model.generate_content_async
+
+  def capturing_generate_content_async(llm_request):
+    captured_requests.append(llm_request)
+    return original_generate_content_async(llm_request)
+
+  judge._judge_model.generate_content_async = capturing_generate_content_async
+
+  actual_invocations = [
+      Invocation(
+          invocation_id="id1",
+          user_content=genai_types.Content(
+              parts=[genai_types.Part(text="user content 1")],
+              role="user",
+          ),
+          final_response=genai_types.Content(
+              parts=[genai_types.Part(text="final response 1")],
+              role="model",
+          ),
+      )
+  ]
+
+  await judge.evaluate_invocations(actual_invocations)
+
+  assert len(captured_requests) == 1
+  config = captured_requests[0].config
+  assert config.automatic_function_calling is not None
+  assert config.automatic_function_calling.disable is True
+
+
 @pytest.mark.asyncio
 async def test_evaluate_invocations_grades_criterion_only_metric(
     mock_judge_model,