Loïc MinaudierSoftware developerDatadog
Agents on GPT-6 Sol with function and MCP tools, called through Chat Completions behind an OpenAI-compatible gateway.
GitHub (openai/openai-agents-python), published Read the issue (opens GitHub (openai/openai-agents-python) in a new tab)
Observation
A Datadog developer's agents on GPT-6 Sol failed on every function tool call until the SDK learned GPT-6 reasoning defaults.
- Takeaway
- Test each new model family with tools before switching the agent's model, since the SDK's defaults are tuned per family.
- What happened
- The SDK applied default reasoning settings only to GPT-5 model names, so GPT-6 agents were sent no reasoning setting. On Chat Completions, GPT-6 Sol then rejected every function tool call with a 400 error, while the same agent code worked on gpt-5.6-luna. The report traced the cause to the default model settings in openai-agents 0.19.2, and the issue is now closed.
- Public engineering write-up (the developer's GitHub issue)
- No team metrics reported
Deployment details
Agents on GPT-6 Sol with function and MCP tools, called through Chat Completions behind an OpenAI-compatible gateway.
- Public engineering write-up (the developer's GitHub issue)
- No team metrics reported
- Team
- Datadog, through an OpenAI-compatible gateway
- Workload
- Agents with function and MCP tools
- Product version
- openai-agents 0.19.2 on Python 3.12
- Model
- GPT-6 Sol
In SignalsCounted once, as the developer's own issue. In the record








