diff --git a/vllm/entrypoints/openai/chat_completion/serving.py b/vllm/entrypoints/openai/chat_completion/serving.py
index 12c43bfeda8..2da89917a8d 100644
--- a/vllm/entrypoints/openai/chat_completion/serving.py
+++ b/vllm/entrypoints/openai/chat_completion/serving.py
@@ -376,7 +376,6 @@ class OpenAIServingChat(OpenAIServing):
                 conversation,
                 tokenizer,
                 request_metadata,
-                reasoning_parser,
                 chat_template_kwargs=chat_template_kwargs,
             )
 
@@ -405,7 +404,6 @@ class OpenAIServingChat(OpenAIServing):
         conversation: list[ConversationMessage],
         tokenizer: TokenizerLike,
         request_metadata: RequestResponseMetadata,
-        reasoning_parser: ReasoningParser | None = None,
         chat_template_kwargs: dict[str, Any] | None = None,
     ) -> AsyncGenerator[str, None]:
         created_time = int(time.time())
@@ -430,33 +428,13 @@ class OpenAIServingChat(OpenAIServing):
         else:
             tool_choice_function_name = None
 
-        # Determine whether tools are in use with "auto" tool choice
-        tool_choice_auto = (
-            not tool_choice_function_name
-            and self._should_stream_with_auto_tool_parsing(request)
-        )
-
-        all_previous_token_ids: list[list[int]] | None
         if self.tool_call_id_type == "kimi_k2":
             history_tool_call_cnt = get_history_tool_calls_cnt(conversation)
         else:
             history_tool_call_cnt = 0
 
-        # Always track previous_texts for comprehensive output logging
         previous_texts = [""] * num_choices
 
-        # Only one of these will be used, thus previous_texts and
-        # all_previous_token_ids will not be used twice in the same iteration.
-        if (
-            tool_choice_auto
-            or tool_choice_function_name
-            or request.tool_choice == "required"
-            or reasoning_parser
-        ):
-            all_previous_token_ids = [[] for _ in range(num_choices)]
-        else:
-            all_previous_token_ids = None
-
         try:
             if self.parser_cls is not None:
                 if tokenizer is None:
@@ -639,26 +617,6 @@ class OpenAIServingChat(OpenAIServing):
 
                     delta_message: DeltaMessage | None
 
-                    # just update previous_texts and previous_token_ids
-                    if (
-                        tool_choice_auto
-                        or tool_choice_function_name
-                        or request.tool_choice == "required"
-                        or reasoning_parser
-                    ):
-                        assert previous_texts is not None
-                        assert all_previous_token_ids is not None
-                        previous_text = previous_texts[i]
-                        previous_token_ids = all_previous_token_ids[i]
-                        current_text = previous_text + delta_text
-                        # avoid the None + list error.
-                        if previous_token_ids:
-                            current_token_ids = previous_token_ids + as_list(
-                                output.token_ids
-                            )
-                        else:
-                            current_token_ids = as_list(output.token_ids)
-
                     if self.use_harmony:
                         delta_message, tools_streamed_flag = (
                             extract_harmony_streaming_delta(
@@ -683,21 +641,7 @@ class OpenAIServingChat(OpenAIServing):
                     else:
                         delta_message = DeltaMessage(content=delta_text)
 
-                    # update the previous values for the next iteration
-                    if (
-                        tool_choice_auto
-                        or tool_choice_function_name
-                        or request.tool_choice == "required"
-                        or reasoning_parser
-                    ) and not self.use_harmony:
-                        assert previous_texts is not None
-                        assert all_previous_token_ids is not None
-                        previous_texts[i] = current_text
-                        all_previous_token_ids[i] = current_token_ids
-                    else:
-                        # Update for comprehensive logging even in simple case
-                        assert previous_texts is not None
-                        previous_texts[i] += delta_text
+                    previous_texts[i] += delta_text
 
                     # set the previous values for the next iteration
                     previous_num_tokens[i] += len(output.token_ids)
@@ -1326,19 +1270,3 @@ class OpenAIServingChat(OpenAIServing):
                 )
 
         return ChatCompletionLogProbs(content=logprobs_content)
-
-    def _should_stream_with_auto_tool_parsing(self, request: ChatCompletionRequest):
-        """
-        Utility function to check if streamed tokens should go through the tool
-        call parser that was configured.
-
-        We only want to do this IF user-provided tools are set, a tool parser
-        is configured, "auto" tool choice is enabled, and the request's tool
-        choice field indicates that "auto" tool choice should be used.
-        """
-        return (
-            request.tools
-            and self.tool_parser
-            and self.enable_auto_tools
-            and request.tool_choice in ["auto", None]
-        )