OpenAI API / OpenAI API
GPT5 Models | Tool choices other than auto are not supported with model
Fix error when specifying explicit tool_choice (e.g., 'required', 'none', or function name) with GPT-5 models, forcing fallback to auto mode Includes evidence for OpenAI API troubleshooting demand.
- Category
- OpenAI API
- Error signature
Tool choices other than 'auto' are not supported with model on GPT5- Quick fix
- Compare the failing environment with a known working setup, then change one configuration value at a time.
- Updated
What this error means
Tool choices other than 'auto' are not supported with model on GPT5 is a OpenAI API failure pattern reported for developers trying to fix error when specifying explicit tool_choice (e.g., ‘required’, ‘none’, or function name) with gpt-5 models, forcing fallback to auto mode. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.
Why this happens
GitHub Issue #2537 on openai/openai-python (opened Aug 9, 2025, by hayescode). GPT-5 models reject non-auto tool choices, breaking function calling patterns for developers who need deterministic tool invocation. 17 comments indicate active community engagement. High value: function calling is core to paid API usage.
Common causes
- GitHub Issue #2537 on openai/openai-python (opened Aug 9, 2025, by hayescode). GPT-5 models reject non-auto tool choices, breaking function calling patterns for developers who need deterministic tool invocation. 17 comments indicate active community engagement. High value: function calling is core to paid API usage.
Quick fixes
- Confirm the exact error signature matches
Tool choices other than 'auto' are not supported with model on GPT5. - Check the OpenAI API account, local tool state, and provider configuration involved in the failing workflow.
- Compare the failing environment with a known working setup, then change one configuration value at a time.
Platform/tool-specific checks
- Verify the command, editor, extension, or API client that produced the error.
- Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
- Avoid deleting credentials, local model data, or project settings until the failing scope is clear.
Step-by-step troubleshooting
- Capture the exact error message and the command, editor action, or request that triggered it.
- Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
- Review the source evidence below and compare it with your environment.
- Apply one change at a time and rerun the smallest failing action.
- Keep the working fix documented for the team or deployment environment.
How to prevent it
- Keep provider/tool configuration documented.
- Record non-secret diagnostics such as tool version, provider name, model name, and command path.
- Add a lightweight check before CI or production workflows depend on the tool.
Sources checked
Evidence note: GitHub Issue #2537 on openai/openai-python (opened Aug 9, 2025, by hayescode). GPT-5 models reject non-auto tool choices, breaking function calling patterns for developers who need deterministic tool invocation. 17 comments indicate active community engagement. High value: function calling is core to paid API usage.
Related errors
- OpenAI API
FAQ
What should I check first?
Start with the exact Tool choices other than 'auto' are not supported with model on GPT5 text and the smallest action that reproduces it.
Can I ignore this error?
No. Treat it as a failed OpenAI API workflow until the root cause is understood.
Is this guaranteed to have one fix?
No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.
How do I know the fix worked?
Rerun the same command, editor action, or request. The fix is working when that action completes without Tool choices other than 'auto' are not supported with model on GPT5.