Claude Sonnet 5.5

Anthropic's best balance of speed and intelligence.

Knowledge cutoff Jun 2026. Adaptive thinking is on by default, with effort levels low, medium, high, xhigh and max. Priced at $0.05/$0.10 per million tokens.

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  "messages": [
    {
      "role": "user",
      "content": "Hello, world."
    }
  ]
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