fix: OpenAIChatGenerator - improve the logic to exclude custom tool calls (#9725)

Author: anakin87

haystack/components/generators/chat/openai.py

@@ -8,7 +8,12 @@
 from typing import Any, Optional, Union
 
 from openai import AsyncOpenAI, AsyncStream, OpenAI, Stream
-from openai.types.chat import ChatCompletion, ChatCompletionChunk, ChatCompletionMessage
+from openai.types.chat import (
+    ChatCompletion,
+    ChatCompletionChunk,
+    ChatCompletionMessage,
+    ChatCompletionMessageCustomToolCall,
+)
 from openai.types.chat.chat_completion import Choice
 from openai.types.chat.chat_completion_chunk import Choice as ChunkChoice
 
@@ -480,7 +485,7 @@ def _convert_chat_completion_to_chat_message(completion: ChatCompletion, choice:
     if message.tool_calls:
         # we currently only support function tools (not custom tools)
         # https://platform.openai.com/docs/guides/function-calling#custom-tools
-        openai_tool_calls = [tc for tc in message.tool_calls if tc.type == "function"]
+        openai_tool_calls = [tc for tc in message.tool_calls if not isinstance(tc, ChatCompletionMessageCustomToolCall)]
         for openai_tc in openai_tool_calls:
             arguments_str = openai_tc.function.arguments
             try:

releasenotes/notes/openai-better-exclude-custom-tcs-35e52e359b248fc8.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    In `OpenAIChatGenerator`, improved the logic to exclude unsupported custom tool calls.
+    The previous implementation caused compatibility issues with the Mistral Haystack core integration,
+    which extends `OpenAIChatGenerator`.