Reduce finish_reason reliance

Non-auto tool choices will result in a finish_reason of "stop" rather than "tool_calls". The current code assumes "stop" means there are no tool calls to be made when this isn't true. Instead, it should simply check for any available tool calls.

Alongside, the last message in a chat completion stream isn't guaranteed to have the finish_reason. Instead we should check for any reasons to stop as we collect chunks and then use that at the end.

Author: Nick-Source

mcp_bridge/openai_clients/chatCompletion.py

@@ -50,7 +50,7 @@ async def chat_completions(
         request.messages.append(msg)
 
         logger.debug(f"finish reason: {response.choices[0].finish_reason}")
-        if response.choices[0].finish_reason.value in ["stop", "length"]:
+        if response.choices[0].finish_reason == "length" or not response.choices[0].message.tool_calls:
             logger.debug("no tool calls found")
             return response
 

mcp_bridge/openai_clients/streamChatCompletion.py

@@ -52,8 +52,7 @@ async def chat_completions(request: CreateChatCompletionRequest, http_request: R
 
         # logger.debug(json_data)
 
-        last: Optional[CreateChatCompletionStreamResponse] = None  # last message
-
+        tool_call: bool = False
         tool_call_name: str = ""
         tool_call_json: str = ""
         should_forward: bool = True
@@ -113,20 +112,16 @@ async def chat_completions(request: CreateChatCompletionRequest, http_request: R
                     content = content if content is not None else ""
                     response_content += content
 
-                    # handle stop reasons
-                    if  len(parsed_data.choices) > 0 and parsed_data.choices[0].finish_reason is not None:
-                        if parsed_data.choices[0].finish_reason.value in [
-                            "stop",
-                            "length",
-                        ]:
-                            fully_done = True
-                        else:
-                            should_forward = False
+                    # handle stopping for length
+                    if len(parsed_data.choices) > 0 and parsed_data.choices[0].finish_reason == "length":
+                        fully_done = True
 
                     # this manages the incoming tool call schema
                     # most of this is assertions to please mypy
-                    if len(parsed_data.choices) > 0 and parsed_data.choices[0].delta.tool_calls is not None:
+                    if len(parsed_data.choices) > 0 and parsed_data.choices[0].delta.tool_calls:
                         should_forward = False
+                        tool_call = True
+
                         assert (
                             parsed_data.choices[0].delta.tool_calls[0].function is not None
                         )
@@ -149,19 +144,14 @@ async def chat_completions(request: CreateChatCompletionRequest, http_request: R
                         logger.debug("forwarding message")
                         yield SSEData.model_validate_json(sse.data).model_dump_json()
 
-                    # save the last message
-                    last = parsed_data
-
-        # ideally we should check this properly
-        assert last is not None
-        if len(last.choices) > 0:
-            assert last.choices[0].finish_reason is not None
-
-        if len(last.choices) > 0 and last.choices[0].finish_reason.value in ["stop", "length"]:
+        if fully_done or tool_call == False:
             logger.debug("no tool calls found")
             fully_done = True
             continue
 
+        # Tool call was found, therefore we aren't done yet
+        fully_done = False
+
         logger.debug("tool calls found")
         logger.debug(
             f"{tool_call_name=} {tool_call_json=}"