ChatCompletionMessageToolCallParam can't not be converted with openai>=1.99.0

[DeoLeung]

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

[moseshu]

same questions, how to solve it ?

[DeoLeung]

same questions, how to solve it ?

downgrade to openai<1.99.0 at the moment

[sajeel0944]

I'm also getting the same error whenever I try to call any tool

[saadii077]

Issue Description:
When using openai-agents v0.2.5 with Python SDK, I encounter the following error:
ChatCompletionMessageToolCallParam can't be converted.

Steps to Reproduce:

1. Install latest openai-agents v0.2.5.
2. Run the provided example code from documentation (Python SDK).
3. Error occurs when sending a tool call message to the agent.

Expected Behavior:
The tool call should be processed without type conversion errors.

Actual Behavior:
The code throws:
TypeError: ChatCompletionMessageToolCallParam can't be converted.

Environment:

• Python version: 3.xx
• openai-agents: 0.2.5
• Operating System: Windows/Linux/Mac

Additional Context:
This error started after updating to v0.2.5 on August 7, 2025.****

[MuheebUrRehman]

I'm experiencing the same issue. Could anyone tell me which OpenAI Agents SDK version this class was changed in, so we can downgrade to that version for now?

[seratch]

This is due to openai package's incompatibility. So, please downgrade openai package (not openai-agents) until #1415 is released.