---
type: email
from: "Zhanzhao (Deo) Liang" <notifications@github.com>
subject: [openai/openai-agents-python] ChatCompletionMessageToolCallParam

 can't not be converted with openai>=1.99.0 (Issue #1401)
received: 2026-03-05 09:55:12
date_header: Fri, 08 Aug 2025 00:11:35 -0700
priority: normal
status: awaiting_approval
uid: 26904
---

## Email Content

**From:** "Zhanzhao (Deo) Liang" <notifications@github.com>
**Subject:** [openai/openai-agents-python] ChatCompletionMessageToolCallParam

 can't not be converted with openai>=1.99.0 (Issue #1401)
**Date:** Fri, 08 Aug 2025 00:11:35 -0700

### Body (preview)

DeoLeung created an issue (openai/openai-agents-python#1401)



```bash

lib/python3.12/site-packages/agents/models/chatcmpl_converter.py", line 443, in items_to_messages

    new_tool_call = ChatCompletionMessageToolCallParam(

                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^



TypeError: Cannot instantiate typing.Union

```



openai `1.99.3` will fail with chat completions, seems the `ChatCompletionMessageToolCallParam` is a union now



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