Pydantic AI thinking=False silently dropped for OpenRouter and other reasoning models

What this error means

model_settings thinking=False silently dropped — reasoning field missing from OpenRouter request body is a OpenRouter failure pattern reported for developers trying to fix pydantic ai silently dropping thinking=false setting when routing through openrouter, xai, or bedrock reasoning models. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Pydantic AI issue #5379 (created 2026-05-12, 3 comments). thinking=False silently dropped for reasoning models routed through OpenRouterModel, xAI, Bedrock. HTTP body contains no reasoning field. No exception or warning thrown — completely silent failure.

Common causes

• Pydantic AI developers set model_settings={‘thinking’: False} to disable reasoning mode, but the setting is silently dropped — no exception, no warning. The HTTP body sent to OpenRouter contains no reasoning field at all. Affects cost control and response behavior for paid API usage
• Pydantic AI issue #5379 (created 2026-05-12, 3 comments). thinking=False silently dropped for reasoning models routed through OpenRouterModel, xAI, Bedrock. HTTP body contains no reasoning field. No exception or warning thrown — completely silent failure.

Quick fixes

1. Confirm the exact error signature matches model_settings thinking=False silently dropped — reasoning field missing from OpenRouter request body.
2. Check the OpenRouter account, local tool state, and provider configuration involved in the failing workflow.
3. 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

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. 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

• https://github.com/pydantic/pydantic-ai/issues/5379

Evidence note: Pydantic AI issue #5379 (created 2026-05-12, 3 comments). thinking=False silently dropped for reasoning models routed through OpenRouterModel, xAI, Bedrock. HTTP body contains no reasoning field. No exception or warning thrown — completely silent failure.

Related errors

• Pydantic AI reasoning mode not working
• OpenRouter thinking parameter ignored
• Pydantic AI model_settings silently ignored

FAQ

What should I check first?

Start with the exact model_settings thinking=False silently dropped — reasoning field missing from OpenRouter request body text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed OpenRouter 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 model_settings thinking=False silently dropped — reasoning field missing from OpenRouter request body.