diff --git a/google/genai/_extra_utils.py b/google/genai/_extra_utils.py
index 98a75748e..2d807aefe 100644
--- a/google/genai/_extra_utils.py
+++ b/google/genai/_extra_utils.py
@@ -530,10 +530,23 @@ def raise_error_for_afc_incompatible_config(config: Optional[types.GenerateConte
     return
   afc_config = config.automatic_function_calling
   disable_afc_config = afc_config.disable if afc_config else False
+  function_calling_config = config.tool_config.function_calling_config
   stream_function_call = (
-      config.tool_config.function_calling_config.stream_function_call_arguments
+      function_calling_config.stream_function_call_arguments
   )
 
+  if (
+      function_calling_config.mode == types.FunctionCallingConfigMode.ANY
+      and not disable_afc_config
+  ):
+    logger.warning(
+        'tool_config.function_calling_config.mode is set to ANY while'
+        ' automatic function calling (AFC) is enabled. AFC will continue'
+        ' calling functions until max_remote_calls is reached, so the model'
+        ' may not return a natural language response. Set mode to AUTO or'
+        ' disable automatic function calling if this is intentional.'
+    )
+
   if stream_function_call and not disable_afc_config:
     raise ValueError(
         'Running in streaming mode with stream_function_call_arguments'
diff --git a/google/genai/tests/afc/test_raise_error_for_afc_incompatible_config.py b/google/genai/tests/afc/test_raise_error_for_afc_incompatible_config.py
index eadadb2b6..3453bd7f3 100644
--- a/google/genai/tests/afc/test_raise_error_for_afc_incompatible_config.py
+++ b/google/genai/tests/afc/test_raise_error_for_afc_incompatible_config.py
@@ -16,6 +16,8 @@
 
 """Tests for raise_error_for_afc_incompatible_config."""
 
+import logging
+
 import pytest
 from ... import types
 from ..._extra_utils import raise_error_for_afc_incompatible_config
@@ -157,3 +159,50 @@ def test_incompatible_config_stream_function_call_arguments_set_no_disable_afc()
             ),
         )
     )
+
+
+@pytest.mark.parametrize(
+    ('mode', 'disable_afc', 'should_warn'),
+    [
+        (types.FunctionCallingConfigMode.ANY, False, True),
+        (types.FunctionCallingConfigMode.ANY, True, False),
+        (types.FunctionCallingConfigMode.AUTO, False, False),
+    ],
+)
+def test_function_calling_mode_warns_when_afc_is_enabled(
+    caplog, mode, disable_afc, should_warn
+):
+  caplog.set_level(logging.WARNING, logger='google_genai.models')
+
+  raise_error_for_afc_incompatible_config(
+      types.GenerateContentConfig(
+          automatic_function_calling=types.AutomaticFunctionCallingConfig(
+              disable=disable_afc,
+          ),
+          tool_config=types.ToolConfig(
+              function_calling_config=types.FunctionCallingConfig(mode=mode),
+          ),
+      )
+  )
+
+  if should_warn:
+    assert 'mode is set to ANY' in caplog.text
+    assert 'automatic function calling' in caplog.text
+  else:
+    assert not caplog.records
+
+
+def test_any_function_calling_mode_warns_when_afc_config_is_unset(caplog):
+  caplog.set_level(logging.WARNING, logger='google_genai.models')
+
+  raise_error_for_afc_incompatible_config(
+      types.GenerateContentConfig(
+          tool_config=types.ToolConfig(
+              function_calling_config=types.FunctionCallingConfig(
+                  mode=types.FunctionCallingConfigMode.ANY,
+              ),
+          ),
+      )
+  )
+
+  assert 'mode is set to ANY' in caplog.text