diff --git a/litellm/completion_extras/litellm_responses_transformation/transformation.py b/litellm/completion_extras/litellm_responses_transformation/transformation.py
index 1b976f5a48b..4024ce5360e 100644
--- a/litellm/completion_extras/litellm_responses_transformation/transformation.py
+++ b/litellm/completion_extras/litellm_responses_transformation/transformation.py
@@ -1115,7 +1115,7 @@ class LiteLLMResponsesTransformationHandler(CompletionTransformationBridge):
         responses_tools: Final[list[ALL_RESPONSES_API_TOOL_PARAMS]] = []
         for tool in tools:
             # convert function tool from chat completion to responses API format
-            if tool.get("type") == "function":
+            if tool.get("type") == "function" and isinstance(tool.get("function"), dict):
                 function_tool = cast(ChatCompletionToolParamFunctionChunk, tool.get("function"))
                 responses_tools.append(
                     FunctionToolParam(
diff --git a/tests/test_litellm/completion_extras/litellm_responses_transformation/test_completion_extras_litellm_responses_transformation_transformation.py b/tests/test_litellm/completion_extras/litellm_responses_transformation/test_completion_extras_litellm_responses_transformation_transformation.py
index c326ad4a0f7..7e03a8886fb 100644
--- a/tests/test_litellm/completion_extras/litellm_responses_transformation/test_completion_extras_litellm_responses_transformation_transformation.py
+++ b/tests/test_litellm/completion_extras/litellm_responses_transformation/test_completion_extras_litellm_responses_transformation_transformation.py
@@ -830,6 +830,24 @@ def test_convert_tools_to_responses_format():
     assert result[0]["name"] == "test"
 
 
+def test_convert_tools_to_responses_format_passes_flat_function_tool_through():
+    from litellm.completion_extras.litellm_responses_transformation.transformation import (
+        LiteLLMResponsesTransformationHandler,
+    )
+
+    handler = LiteLLMResponsesTransformationHandler()
+    flat_tool = {
+        "type": "function",
+        "name": "shell",
+        "description": "Run a shell command",
+        "parameters": {"type": "object", "properties": {"cmd": {"type": "string"}}, "required": ["cmd"]},
+    }
+
+    converted = handler._convert_tools_to_responses_format([flat_tool])
+
+    assert converted == [flat_tool]
+
+
 def test_extract_extra_body_params_reasoning_effort_override():
     """Test that reasoning_effort from extra_body overrides top-level reasoning_effort"""
     from litellm.completion_extras.litellm_responses_transformation.transformation import (