Reasoning

Reasoning models think through a problem before they answer. The thinking takes extra tokens, which you pay for as output, and usually gives better answers on maths, code and multi-step problems.

Reasoning effort

Use reasoning_effort to trade quality for cost and speed. Models that support it take "low", "medium" or "high"; some also take "minimal".

response = client.chat.completions.create(
    model="openai/gpt-6-luna",
    messages=[{"role": "user", "content": "How many prime numbers are there below 100?"}],
    reasoning_effort="low",
)
print(response.choices[0].message.content)
print(response.usage.completion_tokens_details.reasoning_tokens)

reasoning_effort is the only reasoning setting Flow AI passes on. A host’s own reasoning options, such as a thinking budget, are removed from the request.

Seeing the reasoning

Some models return their thinking in message.reasoning_content. Others keep it hidden and only report how many tokens it took, in usage.completion_tokens_details.reasoning_tokens.

Billing

Reasoning tokens are charged as output, even when you can’t see them. Where a model prices reasoning higher than output, the hold uses the higher price. Set max_tokens with room for both the thinking and the answer: if the model runs out while thinking, you pay for the thinking and get no answer.