diff --git a/src/google/adk/models/gemini_context_cache_manager.py b/src/google/adk/models/gemini_context_cache_manager.py
index 801ac1351e..e4cc2f9bfa 100644
--- a/src/google/adk/models/gemini_context_cache_manager.py
+++ b/src/google/adk/models/gemini_context_cache_manager.py
@@ -447,7 +447,7 @@ async def _create_gemini_cache(
 
     with tracer.start_as_current_span("create_cache") as span:
       # Prepare cache contents (first N contents + system instruction + tools)
-      cache_contents = llm_request.contents[:cache_contents_count]
+      cache_contents = llm_request.contents[:cache_contents_count] or None
 
       cache_config = types.CreateCachedContentConfig(
           contents=cache_contents,
diff --git a/tests/unittests/agents/test_gemini_context_cache_manager.py b/tests/unittests/agents/test_gemini_context_cache_manager.py
index 9e67706680..1d95c4e46f 100644
--- a/tests/unittests/agents/test_gemini_context_cache_manager.py
+++ b/tests/unittests/agents/test_gemini_context_cache_manager.py
@@ -989,6 +989,8 @@ async def test_fingerprint_only_metadata_transitions_to_active_cache(
     assert result_2.contents_count == 0  # Preserved from prefix
     assert result_2.invocations_used == 1
     self.manager.genai_client.aio.caches.create.assert_called_once()
+    create_call = self.manager.genai_client.aio.caches.create.call_args
+    assert create_call.kwargs["config"].contents is None
 
   async def test_dynamic_instruction_does_not_break_initial_cache_fingerprint(
       self,