Custom provider request body

Use extra_body to send provider-specific options. When a gateway uses your own provider API key and an OpenAI-compatible provider endpoint, extra_body merges custom JSON into the provider request body:

{
    "model": "my-custom-model:abc4",
    "messages": [
        {
            "role": "user",
            "content": "Explain the tradeoff."
        }
    ],
    "extra_body": {
        "reasoning": {
            "enabled": true
        }
    }
}

extra_body is not allowed with integrated AIVAX models.

Reasoning parameters differ by provider and model. See how to set reasoning effort across providers before choosing provider-specific options.

Use extra_body for options that AIVAX does not expose as a request field, such as a provider’s reasoning switch. Prefer the standard fields, such as reasoning_effort, when they exist, because they also work after you change the provider. The JSON is merged at the root of the provider request and can overwrite fields AIVAX sets, so send only the keys the provider documents.

Send extra_body as a field of the JSON request body. When using the OpenAI Python SDK, nest it inside the SDK’s extra_body argument, as in extra_body={"extra_body": {...}}, because the SDK’s own extra_body only adds fields to the request; see Using via SDKs.