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Reasoning

This page only documents reasoning flows that were verified with real requests against Crazyrouter production. Verification date:
  • 2026-03-22
Verified models:
  • gpt-5.4
  • claude-opus-4-6-thinking
  • gemini-3-pro-preview

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Verified matrix

ModelProtocolEndpointSuccess marker
gpt-5.4OpenAI ResponsesPOST /v1/responsesoutput includes a reasoning item
claude-opus-4-6-thinkingAnthropic MessagesPOST /v1/messagesReturns thinking block
gemini-3-pro-previewGemini NativePOST /v1beta/models/{model}:generateContentusageMetadata includes thoughtsTokenCount

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GPT-5.4

curl https://crazyrouter.com/v1/responses \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "gpt-5.4",
    "input": "Which is larger, 9.11 or 9.9? Explain briefly.",
    "reasoning": {
      "effort": "high",
      "summary": "detailed"
    }
  }'
Verified output types: 
["reasoning", "message"]
Verified reasoning item shape: 
{
  "type": "reasoning",
  "summary": [
    {
      "type": "summary_text",
      "text": "..."
    }
  ]
}

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Claude Opus 4.6 Thinking

curl https://crazyrouter.com/v1/messages \
  -H "Content-Type: application/json" \
  -H "x-api-key: YOUR_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-opus-4-6-thinking",
    "max_tokens": 320,
    "thinking": {
      "type": "enabled",
      "budget_tokens": 128
    },
    "messages": [
      {
        "role": "user",
        "content": "Which is larger, 9.11 or 9.9? Explain briefly."
      }
    ]
  }'
Verified response shape: 
{
  "content": [
    {
      "type": "thinking"
    },
    {
      "type": "text"
    }
  ]
}

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Gemini 3 Pro Preview

curl "https://crazyrouter.com/v1beta/models/gemini-3-pro-preview:generateContent?key=YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [
      {
        "role": "user",
        "parts": [
          {
            "text": "Which is larger, 9.11 or 9.9? Explain briefly."
          }
        ]
      }
    ],
    "generationConfig": {
      "thinkingConfig": {
        "thinkingBudget": 256
      },
      "maxOutputTokens": 512
    }
  }'
Verified production field:
  • usageMetadata.thoughtsTokenCount

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Current exclusions

  • In the current recheck, gpt-5.4 via Chat Completions did not reliably surface reasoning_content, so this page uses the Responses API as the primary GPT example
  • Base claude-opus-4-6 did not return a thinking block in this verification round

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See Also