Thinking Effort

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Set the reasoning effort

{
  "model": "kimi-k3",
  "messages": [{"role": "user", "content": "Derive the general formula for this sequence: 1, 4, 9, 25, 64, ..."}],
  "reasoning_effort": "max"
}

$ curl https://api.moonshot.ai/v1/chat/completions \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearer $MOONSHOT_API_KEY" \
    -d '{
        "model": "kimi-k3",
        "messages": [
            {
                "role": "user",
                "content": "Derive the general formula for this sequence: 1, 4, 9, 25, 64, ..."
            }
        ],
        "reasoning_effort": "max"
    }'

import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["MOONSHOT_API_KEY"],
    base_url="https://api.moonshot.ai/v1",
)

completion = client.chat.completions.create(
    model="kimi-k3",
    messages=[
        {"role": "user", "content": "Derive the general formula for this sequence: 1, 4, 9, 25, 64, ..."},
    ],
    reasoning_effort="max",
)

message = completion.choices[0].message
if hasattr(message, "reasoning_content"):
    print(getattr(message, "reasoning_content"))
print(message.content)

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Stay compatible with OpenAI via reasoning_effort

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Fields

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Notes

• Models differ in their support for thinking sub-fields and their defaults (for example, kimi-k2.6 does not support thinking.effort, and thinking.keep does not preserve historical reasoning by default). See the Model Parameter Reference;
• Lower effort levels, once available, will reduce reasoning_content token consumption and response latency — a good fit for lightweight tasks such as classification, rewriting, and simple Q&A. For now, max is the only available level.

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Related reading

• Kimi K3 API Tool Calling Best Practices: thinking-effort trade-offs in tool-calling scenarios
• Thinking Mode: per-model thinking behavior and Preserved Thinking
• Model Parameter Reference: parameter differences across models