更新日: 2026-06-06

GPT-5 Thinking Mode

This page only documents GPT reasoning behavior that was revalidated against Crazyrouter production on 2026-03-22. The current primary example uses:

gpt-5.5
POST /v1/responses

Claude does not currently support POST /v1/responses. If you are integrating Claude, use POST /v1/messages or POST /v1/chat/completions instead of the request shape on this page.

POST /v1/responses

Basic usage

curl https://api.crazyrouter.com/v1/responses \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "gpt-5.5",
    "input": "Which is larger, 9.11 or 9.9? Explain briefly.",
    "reasoning": {
      "effort": "high",
      "summary": "detailed"
    }
  }'

from openai import OpenAI

client = OpenAI(
    api_key="YOUR_API_KEY",
    base_url="https://api.crazyrouter.com/v1"
)

response = client.responses.create(
    model="gpt-5.5",
    input="Which is larger, 9.11 or 9.9? Explain briefly.",
    reasoning={
        "effort": "high",
        "summary": "detailed"
    }
)

print(response.output_text)

import OpenAI from "openai";

const client = new OpenAI({
  apiKey: "YOUR_API_KEY",
  baseURL: "https://api.crazyrouter.com/v1",
});

const response = await client.responses.create({
  model: "gpt-5.5",
  input: "Which is larger, 9.11 or 9.9? Explain briefly.",
  reasoning: {
    effort: "high",
    summary: "detailed",
  },
});

console.log(response.output_text);

Verified response shape

Verified output.type values:

["reasoning", "message"]

Typical reasoning item shape:

{
  "id": "rs_xxx",
  "type": "reasoning",
  "encrypted_content": "...",
  "summary": [
    {
      "type": "summary_text",
      "text": "..."
    }
  ]
}

The final answer is returned through the message item:

{
  "type": "message",
  "content": [
    {
      "type": "output_text",
      "text": "..."
    }
  ]
}

`reasoning` parameter

Field	Type	Description
`effort`	string	Reasoning intensity. Verified values include `low`, `medium`, and `high`
`summary`	string	Summary granularity. `concise` and `detailed` were revalidated

Practical rule

If you only want stronger reasoning, send effort
If you need an inspectable reasoning summary, send both effort and summary

In the current recheck:

with only effort, the reasoning item existed but summary could be an empty array
with summary: "detailed", summary_text was returned reliably

Extract the thinking summary

Python

response = client.responses.create(
    model="gpt-5.5",
    input="Design a high-concurrency message queue architecture.",
    reasoning={
        "effort": "high",
        "summary": "detailed"
    }
)

for item in response.output:
    if item.type == "reasoning":
        for part in item.summary:
            if part.type == "summary_text":
                print("Thinking summary:", part.text)
    elif item.type == "message":
        for content in item.content:
            if content.type == "output_text":
                print("Final answer:", content.text)

Streaming thinking

The following Responses SSE event names were revalidated in production:

response.reasoning_summary_part.added
response.reasoning_summary_text.delta
response.reasoning_summary_text.done
response.output_text.delta
response.output_text.done
response.completed

Example:

Python

stream = client.responses.create(
    model="gpt-5.5",
    input="Explain briefly why 9.9 is larger than 9.11.",
    reasoning={
        "effort": "high",
        "summary": "detailed"
    },
    stream=True
)

for event in stream:
    if event.type == "response.reasoning_summary_text.delta":
        print(f"[Thinking summary] {event.delta}", end="")
    elif event.type == "response.output_text.delta":
        print(event.delta, end="")

Current recommendation

If you need a visible reasoning field, prefer gpt-5.5 with the Responses API
Do not treat gpt-5.5 Chat Completions reasoning_content as the current primary contract
If you only care about the final answer, Chat Completions with reasoning_effort is still fine

Reasoning mode increases both latency and token usage. Higher effort generally costs more.

Chat - OpenAI

Chat - Claude

Chat - Gemini

Chat - Responses API

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GPT-5 Thinking Mode

GPT-5 Thinking Mode

Basic usage

Verified response shape

`reasoning` parameter

Practical rule

Extract the thinking summary

Streaming thinking

Current recommendation

​GPT-5 Thinking Mode

​Basic usage

​Verified response shape

​reasoning parameter

​Practical rule

​Extract the thinking summary

​Streaming thinking

​Current recommendation

GPT-5 Thinking Mode

Basic usage

Verified response shape

`reasoning` parameter

Practical rule

Extract the thinking summary

Streaming thinking

Current recommendation