[Frontend] Support tool calling and reasoning parser (#14511)

Signed-off-by: WangErXiao <863579016@qq.com>

.buildkite/test-pipeline.yaml

@@ -118,7 +118,7 @@ steps:
   - pytest -v -s entrypoints/llm/test_generate.py # it needs a clean process
   - pytest -v -s entrypoints/llm/test_generate_multiple_loras.py # it needs a clean process
   - VLLM_USE_V1=0 pytest -v -s entrypoints/llm/test_guided_generate.py # it needs a clean process
-  - pytest -v -s entrypoints/openai --ignore=entrypoints/openai/test_oot_registration.py --ignore=entrypoints/openai/correctness/
+  - pytest -v -s entrypoints/openai --ignore=entrypoints/openai/test_oot_registration.py  --ignore=entrypoints/openai/test_chat_with_tool_reasoning.py --ignore=entrypoints/openai/correctness/
   - pytest -v -s entrypoints/test_chat_utils.py
   - VLLM_USE_V1=0 pytest -v -s entrypoints/offline_mode # Needs to avoid interference with other tests
 

docs/source/features/reasoning_outputs.md

@@ -10,10 +10,10 @@ Reasoning models return a additional `reasoning_content` field in their outputs,
 
 vLLM currently supports the following reasoning models:
 
-| Model Series | Parser Name | Structured Output Support |
-|--------------|-------------|------------------|
-| [DeepSeek R1 series](https://huggingface.co/collections/deepseek-ai/deepseek-r1-678e1e131c0169c0bc89728d) | `deepseek_r1` | `guided_json`, `guided_regex` |
-| [QwQ-32B](https://huggingface.co/Qwen/QwQ-32B) | `deepseek_r1` | `guided_json`, `guided_regex` |
+| Model Series | Parser Name | Structured Output Support | Tool Calling |
+|--------------|-------------|------------------|-------------|
+| [DeepSeek R1 series](https://huggingface.co/collections/deepseek-ai/deepseek-r1-678e1e131c0169c0bc89728d) | `deepseek_r1` | `guided_json`, `guided_regex` | ❌ |
+| [QwQ-32B](https://huggingface.co/Qwen/QwQ-32B) | `deepseek_r1` | `guided_json`, `guided_regex` | ✅ |
 
 ## Quickstart
 
@@ -170,10 +170,51 @@ print("reasoning_content: ", completion.choices[0].message.reasoning_content)
 print("content: ", completion.choices[0].message.content)
 ```
 
+## Tool Calling
+
+The reasoning content is also available when both tool calling and the reasoning parser are enabled. Additionally, tool calling only parses functions from the `content` field, not from the `reasoning_content`.
+
+```python
+from openai import OpenAI
+
+client = OpenAI(base_url="http://localhost:8000/v1", api_key="dummy")
+
+tools = [{
+    "type": "function",
+    "function": {
+        "name": "get_weather",
+        "description": "Get the current weather in a given location",
+        "parameters": {
+            "type": "object",
+            "properties": {
+                "location": {"type": "string", "description": "City and state, e.g., 'San Francisco, CA'"},
+                "unit": {"type": "string", "enum": ["celsius", "fahrenheit"]}
+            },
+            "required": ["location", "unit"]
+        }
+    }
+}]
+
+response = client.chat.completions.create(
+    model=client.models.list().data[0].id,
+    messages=[{"role": "user", "content": "What's the weather like in San Francisco?"}],
+    tools=tools,
+    tool_choice="auto"
+)
+
+print(response)
+tool_call = response.choices[0].message.tool_calls[0].function
+
+print(f"reasoning_content: {response.choices[0].message.reasoning_content}")
+print(f"Function called: {tool_call.name}")
+print(f"Arguments: {tool_call.arguments}")
+```
+
+For more examples, please refer to <gh-file:examples/online_serving/openai_chat_completion_tool_calls_with_reasoning.py> .
+
 ## Limitations
 
 - The reasoning content is only available for online serving's chat completion endpoint (`/v1/chat/completions`).
-- It is not compatible with [`tool_calling`](#tool_calling).
 
 ## How to support a new reasoning model
 

examples/online_serving/openai_chat_completion_tool_calls_with_reasoning.py

+# SPDX-License-Identifier: Apache-2.0
+"""
+An example demonstrates how to use tool calling with reasoning models 
+like QwQ-32B. The reasoning_content will not be parsed by the tool 
+calling process; only the final output will be parsed.
+
+To run this example, you need to start the vLLM server with both 
+the reasoning parser and tool calling enabled.
+
+```bash
+vllm serve Qwen/QwQ-32B \
+     --enable-reasoning --reasoning-parser deepseek_r1 \
+     --enable-auto-tool-choice --tool-call-parser hermes
+     
+```
+
+"""
+
+from openai import OpenAI
+
+
+# Now, simulate a tool call
+def get_current_weather(city: str, state: str, unit: 'str'):
+    return ("The weather in Dallas, Texas is 85 degrees fahrenheit. It is "
+            "partly cloudly, with highs in the 90's.")
+
+
+available_tools = {"get_current_weather": get_current_weather}
+
+# Modify OpenAI's API key and API base to use vLLM's API server.
+openai_api_key = "EMPTY"
+openai_api_base = "http://localhost:8000/v1"
+
+client = OpenAI(
+    api_key=openai_api_key,
+    base_url=openai_api_base,
+)
+
+models = client.models.list()
+model = models.data[0].id
+
+tools = [{
+    "type": "function",
+    "function": {
+        "name": "get_current_weather",
+        "description": "Get the current weather in a given location",
+        "parameters": {
+            "type": "object",
+            "properties": {
+                "city": {
+                    "type":
+                    "string",
+                    "description":
+                    "The city to find the weather for, e.g. 'San Francisco'"
+                },
+                "state": {
+                    "type":
+                    "string",
+                    "description":
+                    "the two-letter abbreviation for the state that the city is"
+                    " in, e.g. 'CA' which would mean 'California'"
+                },
+                "unit": {
+                    "type": "string",
+                    "description": "The unit to fetch the temperature in",
+                    "enum": ["celsius", "fahrenheit"]
+                }
+            },
+            "required": ["city", "state", "unit"]
+        }
+    }
+}]
+messages = [{
+    "role": "user",
+    "content": "Hi! How are you doing today?"
+}, {
+    "role": "assistant",
+    "content": "I'm doing well! How can I help you?"
+}, {
+    "role":
+    "user",
+    "content":
+    "Can you tell me what the temperate will be in Dallas, in fahrenheit?"
+}]
+
+
+def extract_reasoning_and_calls(chunks: list):
+    reasoning_content = ""
+    tool_call_idx = -1
+    arguments = []
+    function_names = []
+    for chunk in chunks:
+        if chunk.choices[0].delta.tool_calls:
+            tool_call = chunk.choices[0].delta.tool_calls[0]
+            if tool_call.index != tool_call_idx:
+                tool_call_idx = chunk.choices[0].delta.tool_calls[0].index
+                arguments.append("")
+                function_names.append("")
+
+            if tool_call.function:
+                if tool_call.function.name:
+                    function_names[tool_call_idx] = tool_call.function.name
+
+                if tool_call.function.arguments:
+                    arguments[tool_call_idx] += tool_call.function.arguments
+        else:
+            if hasattr(chunk.choices[0].delta, "reasoning_content"):
+                reasoning_content += chunk.choices[0].delta.reasoning_content
+    return reasoning_content, arguments, function_names
+
+
+print("---------Full Generate With Automatic Function Calling-------------")
+tool_calls = client.chat.completions.create(messages=messages,
+                                            model=model,
+                                            tools=tools)
+print(f"reasoning_content: {tool_calls.choices[0].message.reasoning_content}")
+print(f"function name: "
+      f"{tool_calls.choices[0].message.tool_calls[0].function.name}")
+print(f"function arguments: "
+      f"{tool_calls.choices[0].message.tool_calls[0].function.arguments}")
+
+print("----------Stream Generate With Automatic Function Calling-----------")
+tool_calls_stream = client.chat.completions.create(messages=messages,
+                                                   model=model,
+                                                   tools=tools,
+                                                   stream=True)
+chunks = []
+for chunk in tool_calls_stream:
+    chunks.append(chunk)
+
+reasoning_content, arguments, function_names = extract_reasoning_and_calls(
+    chunks)
+
+print(f"reasoning_content: {reasoning_content}")
+print(f"function name: {function_names[0]}")
+print(f"function arguments: {arguments[0]}")
+
+print("----------Full Generate With Named Function Calling-----------------")
+tool_calls = client.chat.completions.create(messages=messages,
+                                            model=model,
+                                            tools=tools,
+                                            tool_choice={
+                                                "type": "function",
+                                                "function": {
+                                                    "name":
+                                                    "get_current_weather"
+                                                }
+                                            })
+
+tool_call = tool_calls.choices[0].message.tool_calls[0].function
+print(f"reasoning_content: {tool_calls.choices[0].message.reasoning_content}")
+print(f"function name: {tool_call.name}")
+print(f"function arguments: {tool_call.arguments}")
+print("----------Stream Generate With Named Function Calling--------------")
+
+tool_calls_stream = client.chat.completions.create(
+    messages=messages,
+    model=model,
+    tools=tools,
+    tool_choice={
+        "type": "function",
+        "function": {
+            "name": "get_current_weather"
+        }
+    },
+    stream=True)
+
+chunks = []
+for chunk in tool_calls_stream:
+    chunks.append(chunk)
+
+reasoning_content, arguments, function_names = extract_reasoning_and_calls(
+    chunks)
+print(f"reasoning_content: {reasoning_content}")
+print(f"function name: {function_names[0]}")
+print(f"function arguments: {arguments[0]}")
+print("\n\n")

tests/entrypoints/openai/test_chat_with_tool_reasoning.py

+# SPDX-License-Identifier: Apache-2.0
+
+import openai  # use the official client for correctness check
+import pytest
+import pytest_asyncio
+
+from ...utils import RemoteOpenAIServer
+
+# a reasoning and tool calling model
+MODEL_NAME = "Qwen/QwQ-32B"
+
+
+@pytest.fixture(scope="module")
+def server():  # noqa: F811
+    args = [
+        "--max-model-len", "8192", "--enforce-eager", "--enable-reasoning",
+        "--reasoning-parser", "deepseek_r1", "--enable-auto-tool-choice",
+        "--tool-call-parser", "hermes"
+    ]
+
+    with RemoteOpenAIServer(MODEL_NAME, args) as remote_server:
+        yield remote_server
+
+
+@pytest_asyncio.fixture
+async def client(server):
+    async with server.get_async_client() as async_client:
+        yield async_client
+
+
+TOOLS = [{
+    "type": "function",
+    "function": {
+        "name": "get_current_weather",
+        "description": "Get the current weather in a given location",
+        "parameters": {
+            "type": "object",
+            "properties": {
+                "city": {
+                    "type":
+                    "string",
+                    "description":
+                    "The city to find the weather for, e.g. 'San Francisco'"
+                },
+                "state": {
+                    "type":
+                    "string",
+                    "description":
+                    "the two-letter abbreviation for the state that the city is"
+                    " in, e.g. 'CA' which would mean 'California'"
+                },
+                "unit": {
+                    "type": "string",
+                    "description": "The unit to fetch the temperature in",
+                    "enum": ["celsius", "fahrenheit"]
+                }
+            },
+            "required": ["city", "state", "unit"]
+        }
+    }
+}]
+
+MESSAGES = [{
+    "role": "user",
+    "content": "Hi! How are you doing today?"
+}, {
+    "role": "assistant",
+    "content": "I'm doing well! How can I help you?"
+}, {
+    "role":
+    "user",
+    "content":
+    "Can you tell me what the temperate will be in Dallas, in fahrenheit?"
+}]
+
+FUNC_NAME = "get_current_weather"
+FUNC_ARGS = """{"city": "Dallas", "state": "TX", "unit": "fahrenheit"}"""
+
+
+def extract_reasoning_and_calls(chunks: list):
+    reasoning_content = ""
+    tool_call_idx = -1
+    arguments = []
+    function_names = []
+    for chunk in chunks:
+        if chunk.choices[0].delta.tool_calls:
+            tool_call = chunk.choices[0].delta.tool_calls[0]
+            if tool_call.index != tool_call_idx:
+                tool_call_idx = chunk.choices[0].delta.tool_calls[0].index
+                arguments.append("")
+                function_names.append("")
+
+            if tool_call.function:
+                if tool_call.function.name:
+                    function_names[tool_call_idx] = tool_call.function.name
+
+                if tool_call.function.arguments:
+                    arguments[tool_call_idx] += tool_call.function.arguments
+        else:
+            if hasattr(chunk.choices[0].delta, "reasoning_content"):
+                reasoning_content += chunk.choices[0].delta.reasoning_content
+    return reasoning_content, arguments, function_names
+
+
+# test streaming
+@pytest.mark.asyncio
+async def test_chat_streaming_of_tool_and_reasoning(
+        client: openai.AsyncOpenAI):
+
+    stream = await client.chat.completions.create(
+        model=MODEL_NAME,
+        messages=MESSAGES,
+        tools=TOOLS,
+        temperature=0.0,
+        stream=True,
+    )
+
+    chunks = []
+    async for chunk in stream:
+        chunks.append(chunk)
+
+    reasoning_content, arguments, function_names = extract_reasoning_and_calls(
+        chunks)
+    assert len(reasoning_content) > 0
+    assert len(function_names) > 0 and function_names[0] == FUNC_NAME
+    assert len(arguments) > 0 and arguments[0] == FUNC_ARGS
+
+
+# test full generate
+@pytest.mark.asyncio
+async def test_chat_full_of_tool_and_reasoning(client: openai.AsyncOpenAI):
+
+    tool_calls = await client.chat.completions.create(
+        model=MODEL_NAME,
+        messages=MESSAGES,
+        tools=TOOLS,
+        temperature=0.0,
+        stream=False,
+    )
+
+    assert len(tool_calls.choices[0].message.reasoning_content) > 0
+    assert tool_calls.choices[0].message.tool_calls[0].function.name \
+          == FUNC_NAME
+    assert tool_calls.choices[0].message.tool_calls[0].function.arguments \
+          == FUNC_ARGS

vllm/entrypoints/openai/cli_args.py

@@ -289,13 +289,6 @@ def validate_parsed_serve_args(args: argparse.Namespace):
         raise TypeError("Error: --enable-reasoning requires "
                         "--reasoning-parser")
 
-    # Ref https://api-docs.deepseek.com/guides/reasoning_model
-    # tool call and reasoning cannot be enabled at the same time.
-    if args.enable_auto_tool_choice and args.enable_reasoning:
-        raise TypeError(
-            "Error: --enable-auto-tool-choice and "
-            "--enable-reasoning cannot be enabled at the same time")
-
 
 def create_parser_for_docs() -> FlexibleArgumentParser:
     parser_for_docs = FlexibleArgumentParser(

vllm/entrypoints/openai/reasoning_parsers/abs_reasoning_parsers.py

 # SPDX-License-Identifier: Apache-2.0
 
 import os
+from abc import abstractmethod
 from collections.abc import Sequence
 from functools import cached_property
 from typing import Callable, Optional, Union
@@ -76,6 +77,40 @@ class ReasoningParser:
             "AbstractReasoningParser.extract_reasoning_content_streaming "
             "has not been implemented!")
 
+    # TODO: need to rebase by PR #14428
+    @abstractmethod
+    def is_reasoning_end(self, input_ids: list[int]) -> bool:
+        """
+        Check if the reasoning content ends in the input_ids.
+        Parameters:
+        input_ids: list[int]
+            The input_ids of the model output.
+        Returns:
+        bool
+            True if the reasoning content ends in the input_ids.
+        """
+
+        raise NotImplementedError(
+            "AbstractReasoningParser.is_reasoning_end has"
+            "not been implemented!")
+
+    # TODO: need to rebase by PR #14428
+    @abstractmethod
+    def extract_content_ids(self, input_ids: list[int]) -> list[int]:
+        """
+        Extract content token ids from the input_ids.
+        Parameters:
+        input_ids: list[int]
+            The input_ids of the model output.
+        Returns:
+        list[int]
+            The extracted content from the input_ids.
+        """
+
+        raise NotImplementedError(
+            "AbstractReasoningParser.extract_content_ids has"
+            " not been implemented!")
+
 
 class ReasoningParserManager:
     reasoning_parsers: dict[str, type] = {}

vllm/entrypoints/openai/reasoning_parsers/deepseek_r1_reasoning_parser.py

@@ -45,6 +45,19 @@ class DeepSeekR1ReasoningParser(ReasoningParser):
                 "DeepSeek R1 reasoning parser could not locate think start/end "
                 "tokens in the tokenizer!")
 
+    # TODO: need to rebase by PR #14428
+    def is_reasoning_end(self, input_ids: list[int]) -> bool:
+        return self.think_end_token_id in input_ids
+
+    def extract_content_ids(self, input_ids: list[int]) -> list[int]:
+        """
+        Extract the content after the end tokens
+        """
+        if self.think_end_token_id not in input_ids[:-1]:
+            return []
+        else:
+            return input_ids[input_ids.index(self.think_end_token_id) + 1:]
+
     def extract_reasoning_content_streaming(
         self,
         previous_text: str,

vllm/entrypoints/openai/serving_chat.py

@@ -328,6 +328,9 @@ class OpenAIServingChat(OpenAIServing):
             # These are only required in "auto" tool choice case
             previous_texts = [""] * num_choices
             all_previous_token_ids = [[]] * num_choices
+            # For reasoning parser and tool call all enabled
+            added_content_delta_arr = [False] * num_choices
+            reasoning_end_arr = [False] * num_choices
         else:
             previous_texts, all_previous_token_ids = None, None
 
@@ -477,8 +480,49 @@ class OpenAIServingChat(OpenAIServing):
 
                     delta_message: Optional[DeltaMessage]
 
+                    # just update previous_texts and previous_token_ids
+                    if tool_choice_auto or should_stream_with_reasoning_parsing:
+                        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
+                        current_token_ids = previous_token_ids + list(
+                            output.token_ids)
+
                     # handle streaming deltas for tools with named tool_choice
                     if tool_choice_function_name:
+                        if (self.enable_reasoning
+                                and not reasoning_parser.is_reasoning_end(
+                                    previous_token_ids)):
+                            assert reasoning_parser is not None
+                            delta_message = (
+                                reasoning_parser.
+                                extract_reasoning_content_streaming(
+                                    previous_text,
+                                    current_text,
+                                    delta_text,
+                                    previous_token_ids,
+                                    current_token_ids,
+                                    output.token_ids,
+                                ))
+                            # When encountering think end id in delta_token_ids,
+                            # process the `content`. Only keep 'content',
+                            # remove 'reasoning_content'
+                            if reasoning_parser.is_reasoning_end(
+                                    list(output.token_ids)):
+                                if delta_message and delta_message.content:
+                                    # This need to be added to next `delta_text`
+                                    current_text = delta_message.content
+                                    delta_message.content = None
+                                else:
+                                    current_text = ""
+                        else:
+                            # Just to add remaining `content`
+                            if self.enable_reasoning:
+                                delta_text = previous_text + delta_text
+                                current_text = ""
+
                             delta_message = DeltaMessage(tool_calls=[
                                 DeltaToolCall(function=DeltaFunctionCall(
                                     name=tool_choice_function_name,
@@ -487,17 +531,65 @@ class OpenAIServingChat(OpenAIServing):
                             ])
 
                     # handle streaming deltas for tools with "auto" tool choice
-                    elif tool_choice_auto:
-                        assert previous_texts is not None
-                        assert all_previous_token_ids is not None
+                    # and reasoning parser
+                    elif tool_choice_auto and self.enable_reasoning:
                         assert tool_parser is not None
-                        #TODO optimize manipulation of these lists
-                        previous_text = previous_texts[i]
-                        previous_token_ids = all_previous_token_ids[i]
-                        current_text = previous_text + delta_text
-                        current_token_ids = previous_token_ids + list(
-                            output.token_ids)
+                        assert reasoning_parser is not None
+                        assert added_content_delta_arr is not None
+                        assert reasoning_end_arr is not None
+                        if not reasoning_end_arr[i]:
+                            delta_message = (
+                                reasoning_parser.
+                                extract_reasoning_content_streaming(
+                                    previous_text,
+                                    current_text,
+                                    delta_text,
+                                    previous_token_ids,
+                                    current_token_ids,
+                                    output.token_ids,
+                                ))
+
+                            # When encountering think end id in delta_token_ids,
+                            # set reasoning status to end.
+                            # Remove the text and token ids related
+                            # to 'reasoning_content'.
+                            if reasoning_parser.is_reasoning_end(
+                                    list(output.token_ids)):
+                                reasoning_end_arr[i] = True
+                                current_token_ids =  \
+                                    reasoning_parser.extract_content_ids(
+                                        list(output.token_ids))
+                                if delta_message and delta_message.content:
+                                    current_text = delta_message.content
+                                    delta_message.content = None
+                                else:
+                                    current_text = ""
+
+                        # handle tool calls only after reasoning is done,
+                        else:
+                            delta_token_ids = list(output.token_ids)
+                            # First time to tool call,
+                            # add the remaining text and token ids
+                            # to delta from previous
+                            if not added_content_delta_arr[i]:
+                                added_content_delta_arr[i] = True
+                                previous_text = ""
+                                previous_token_ids = []
+                                delta_text = current_text
+                                delta_token_ids = current_token_ids
 
+                            delta_message = (
+                                tool_parser.extract_tool_calls_streaming(
+                                    previous_text=previous_text,
+                                    current_text=current_text,
+                                    delta_text=delta_text,
+                                    previous_token_ids=previous_token_ids,
+                                    current_token_ids=current_token_ids,
+                                    delta_token_ids=delta_token_ids,
+                                    request=request))
+                    # when only tool calls
+                    elif tool_choice_auto:
+                        assert tool_parser is not None
                         delta_message = (
                             tool_parser.extract_tool_calls_streaming(
                                 previous_text=previous_text,
@@ -507,23 +599,9 @@ class OpenAIServingChat(OpenAIServing):
                                 current_token_ids=current_token_ids,
                                 delta_token_ids=output.token_ids,
                                 request=request))
-
-                        # update the previous values for the next iteration
-                        previous_texts[i] = current_text
-                        all_previous_token_ids[i] = current_token_ids
-                    # reasoning_content cannot be enabled with tool_choice.
-                    # If it is, the tool_choice will be used instead.
+                    # when only reasoning
                     elif self.enable_reasoning:
-                        # handle reasoning_content delta
                         assert reasoning_parser is not None
-                        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
-                        current_token_ids = previous_token_ids + list(
-                            output.token_ids)
-
                         delta_message = (reasoning_parser.
                                          extract_reasoning_content_streaming(
                                              previous_text,
@@ -533,15 +611,17 @@ class OpenAIServingChat(OpenAIServing):
                                              current_token_ids,
                                              output.token_ids,
                                          ))
+                    # handle streaming just a content delta
+                    else:
+                        delta_message = DeltaMessage(content=delta_text)
 
                     # update the previous values for the next iteration
+                    if tool_choice_auto or should_stream_with_reasoning_parsing:
+                        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
 
-                    # handle streaming just a content delta
-                    else:
-                        delta_message = DeltaMessage(content=delta_text)
-
                     # set the previous values for the next iteration
                     previous_num_tokens[i] += len(output.token_ids)
 
@@ -739,24 +819,24 @@ class OpenAIServingChat(OpenAIServing):
                 except RuntimeError as e:
                     logger.exception("Error in reasoning parser creation.")
                     return self.create_error_response(str(e))
-
+                # If the reasoning parser is enabled,
+                # tool calls are extracted exclusively from the content.
                 reasoning_content, content = (
                     reasoning_parser.extract_reasoning_content(
                         output.text, request=request))
-
-                if reasoning_content:
-                    message = ChatMessage(role=role,
-                                          content=content,
-                                          reasoning_content=reasoning_content)
             else:
-                    message = ChatMessage(role=role, content=output.text)
+                reasoning_content = None
+                content = output.text
 
             # if auto tools are not enabled, and a named tool choice using
             #   outlines is not being used
-            elif (not self.enable_auto_tools
+            if (not self.enable_auto_tools
                     or not self.tool_parser) and not isinstance(
-                      request.tool_choice, ChatCompletionNamedToolChoiceParam):
-                message = ChatMessage(role=role, content=output.text)
+                        request.tool_choice,
+                        ChatCompletionNamedToolChoiceParam):
+                message = ChatMessage(role=role,
+                                      reasoning_content=reasoning_content,
+                                      content=content)
 
             # if the request uses tools and specified a tool choice
             elif request.tool_choice and type(
@@ -766,18 +846,21 @@ class OpenAIServingChat(OpenAIServing):
                     tokenizer, MistralTokenizer) else ToolCall
                 message = ChatMessage(
                     role=role,
+                    reasoning_content=reasoning_content,
                     content="",
                     tool_calls=[
                         tool_call_class(function=FunctionCall(
                             name=request.tool_choice.function.name,
-                            arguments=output.text))
+                            arguments=content))
                     ])
 
             # if the request doesn't use tool choice
             # OR specifies to not use a tool
             elif not request.tool_choice or request.tool_choice == "none":
 
-                message = ChatMessage(role=role, content=output.text)
+                message = ChatMessage(role=role,
+                                      reasoning_content=reasoning_content,
+                                      content=content)
 
             # handle when there are tools and tool choice is auto
             elif request.tools and (
@@ -792,20 +875,23 @@ class OpenAIServingChat(OpenAIServing):
                     return self.create_error_response(str(e))
 
                 tool_call_info = tool_parser.extract_tool_calls(
-                    output.text, request=request)
+                    content if content is not None else "", request=request)
                 # In the OpenAI API the finish_reason is "tools_called"
                 # if the tool choice is auto and the model produced a tool
                 # call. The same is not true for named function calls
                 auto_tools_called = tool_call_info.tools_called
                 if tool_call_info.tools_called:
                     message = ChatMessage(role=role,
+                                          reasoning_content=reasoning_content,
                                           content=tool_call_info.content,
                                           tool_calls=tool_call_info.tool_calls)
 
                 else:
                     # FOR NOW make it a chat message; we will have to detect
                     # the type to make it later.
-                    message = ChatMessage(role=role, content=output.text)
+                    message = ChatMessage(role=role,
+                                          reasoning_content=reasoning_content,
+                                          content=content)
 
             # undetermined case that is still important to handle
             else:
@@ -813,7 +899,9 @@ class OpenAIServingChat(OpenAIServing):
                     "Error in chat_completion_full_generator - cannot determine"
                     " if tools should be extracted. Returning a standard chat "
                     "completion.")
-                message = ChatMessage(role=role, content=output.text)
+                message = ChatMessage(role=role,
+                                      reasoning_content=reasoning_content,
+                                      content=content)
 
             choice_data = ChatCompletionResponseChoice(
                 index=output.index,