Reasoning

Control the thinking of reasoning models, read their reasoning and its tokens.

Reasoning models think before they answer. Models with the Reasoning capability in the catalog support it.

Control the effort

{
  "model": "openai/gpt-oss-120b",
  "messages": [{ "role": "user", "content": "Is 1001 a prime number?" }],
  "reasoning": { "effort": "low" },
  "max_tokens": 4000
}

Field of `reasoning`	Meaning
`effort`	`minimal`, `low`, `medium` or `high`: how much the model thinks.
`max_tokens`	A token budget for thinking, for models that take one instead of `effort`.
`exclude`	`true`: the model still thinks, but the reasoning is not returned.
`enabled`	`false` turns thinking off where the model allows it.

reasoning_effort (the OpenAI field) works as a shortcut for effort.

In the Russia region only the effort is kept: the router sends reasoning.effort as reasoning_effort and drops the rest of reasoning.

Read the reasoning

When the model returns its reasoning, it comes in message.reasoning (or reasoning_content, depending on the model); in a stream, in delta.reasoning or delta.reasoning_content.

Tokens and cost

Reasoning tokens are output tokens: they are billed at the output price and count toward max_tokens. With the default limit of 4096 a model may spend it all on thinking and end with finish_reason: "length" and an empty answer, so set max_tokens generously.

usage.completion_tokens_details.reasoning_tokens shows how many of the output tokens were reasoning.