diff --git a/litellm/llms/chatgpt/responses/transformation.py b/litellm/llms/chatgpt/responses/transformation.py
index c5f67b78654..2fbbffde1ef 100644
--- a/litellm/llms/chatgpt/responses/transformation.py
+++ b/litellm/llms/chatgpt/responses/transformation.py
@@ -66,13 +66,14 @@ class ChatGPTResponsesAPIConfig(OpenAIResponsesAPIConfig):
         litellm_params: GenericLiteLLMParams,
         headers: dict,
     ) -> dict:
-        # The Responses API accepts a string or a list, but this backend
-        # rejects a string with {"detail": "Input must be a list"}.
-        if isinstance(input, str):
-            input = [{"role": "user", "content": input}]  # mutable-ok: the wire payload this backend requires
+        coerced_input: Final = (
+            [{"role": "user", "content": input}]  # mutable-ok: the wire shape this backend accepts
+            if isinstance(input, str)
+            else input
+        )
         request: Final = super().transform_responses_api_request(
             model,
-            input,
+            coerced_input,
             response_api_optional_request_params,
             litellm_params,
             headers,
@@ -103,8 +104,6 @@ class ChatGPTResponsesAPIConfig(OpenAIResponsesAPIConfig):
             "reasoning",
             "previous_response_id",
             "truncation",
-            # The chat-to-responses bridge translates response_format into
-            # "text"; dropping it here discards strict schemas silently.
             "text",
         }