diff --git a/src/google/adk/models/lite_llm.py b/src/google/adk/models/lite_llm.py
index 2a33ba70a6..3b0eb42e6e 100644
--- a/src/google/adk/models/lite_llm.py
+++ b/src/google/adk/models/lite_llm.py
@@ -3038,7 +3038,7 @@ def _finalize_tool_call_response(
         llm_response = _message_to_generate_content_response(
             ChatCompletionAssistantMessage(
                 role="assistant",
-                content="".join(text_parts),
+                content=None,
                 tool_calls=tool_calls,
             ),
             model_version=model_version,
diff --git a/tests/unittests/models/test_litellm.py b/tests/unittests/models/test_litellm.py
index bd1729c639..5591db845b 100644
--- a/tests/unittests/models/test_litellm.py
+++ b/tests/unittests/models/test_litellm.py
@@ -4211,7 +4211,7 @@ async def test_generate_content_async_stream_grounding_metadata(
 
 
 @pytest.mark.asyncio
-async def test_generate_content_async_stream_with_usage_metadata(
+async def test_generate_content_async_stream_tool_call_omits_aggregated_text(
     mock_completion, lite_llm_instance
 ):
 
@@ -4234,6 +4234,7 @@ async def test_generate_content_async_stream_with_usage_metadata(
   assert responses[2].content.parts[0].text == "two:"
   assert responses[2].model_version == "test_model"
   assert responses[3].content.role == "model"
+  assert len(responses[3].content.parts) == 1
   assert responses[3].content.parts[-1].function_call.name == "test_function"
   assert responses[3].content.parts[-1].function_call.args == {
       "test_arg": "test_value"