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Code: tool_choice_required_unsupported HTTP status: 400 Type: invalid_request

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When it fires

Your chat request set tool_choice: "required", but the selected model’s aurous_metadata.capabilities doesn’t include the tool_choice_required flag. The model can still call tools when tool_choice is "auto" or a specific function pin — it just can’t be FORCED into a tool call.

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How to recover

Either pick a model whose capabilities include tool_choice_required (check GET /v1/models), or change your request to use tool_choice: "auto" and accept that the model may answer directly when it judges a tool isn’t necessary.