Claude models are back: Opus 5.5, Sonnet 5.5

• Published: October 18, 2026
• Last verified: October 18, 2026
• Status: active; available in the default and claude_code token groups

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Key details

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Models and prices

• Prompt caching is supported. Cache-read prices are in the model catalog, and cache writes cost 1.25× the input price.
• When a claude-haiku-5-5 prompt exceeds 100,000 tokens, counting cache reads and writes, the whole request is billed at $0.5 input and $2.5 output. See tiered pricing in the catalog.
• Current prices are in the model catalog and on the console pricing page.

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Make a request

export LAOZHANG_API_KEY="YOUR_LAOZHANG_API_KEY"

curl https://api.laozhang.ai/v1/messages \
  -H "Authorization: Bearer $LAOZHANG_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{
    "model": "claude-sonnet-5-5",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "Explain a database index in one sentence."}
    ]
  }'

curl https://api.laozhang.ai/v1/chat/completions \
  -H "Authorization: Bearer $LAOZHANG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-5-5",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "Explain a database index in one sentence."}
    ]
  }'

• In the Anthropic Messages format, the answer is in the content[] blocks whose type is text. In the OpenAI-compatible format, it is in choices[0].message.content.
• For streaming, tool use, and prompt caching, see the Claude protocol reference.
• For a complete Claude Code configuration, see Claude Code setup with LaoZhang API.
• Check token usage and the charge for each request in call logs.

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Current limits

• Each response is capped at 32,768 output tokens. A larger max_tokens is reduced to the cap.
• document content blocks, such as PDFs, are not supported. Extract the text and send it instead.
• Anthropic server tools such as web_search, web_fetch, and code_execution are not supported, and requests that declare them return 400. Claude Code’s WebSearch tool doesn’t work for the same reason.
• /v1/messages/count_tokens, Message Batches, and the Files API are not available.

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Who this affects

• Applies to: projects that call Claude models through LaoZhang API, and anyone using Claude Code or the Anthropic SDKs. Any API key in the default or claude_code group with the Usage first or Usage-based billing mode can call these models.
• Unchanged: no existing model changed. Integrations that call glm-5.2 or deepseek-v4-pro over Anthropic Messages keep working as they are.

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FAQ

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Why does claude-haiku-4-5 return a 503?

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What should I do about an occasional 529?

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Do I need an Anthropic account?

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Sources and related links

• Anthropic pricing: official list prices and cache multipliers.
• Model catalog: current LaoZhang API prices.
• Console pricing: sign in to see the prices that apply to your account.
• Claude protocol: Anthropic Messages API
• Claude Code setup with LaoZhang API
• Latest announcements