Claude Sonnet 5.5

Claude Sonnet 5.5 is Anthropic's Sonnet-class model for well-scoped everyday work, succeeding Claude Sonnet 5 as a direct upgrade. It is especially strong at building features, fixing bugs, and producing polished documents, slides, and spreadsheets, and it writes and communicates more clearly than its predecessor. Thinking is always on, so effort is the main lever for trading off depth, latency, and cost, and lower effort settings keep it responsive for everyday agentic loops.

ChatAnthropic1M tokens$2.1801 / $10.9006 · 1M

anthropic/claude-sonnet-5.5

Context
1M tokens
Completion cap
128,000
Tools
Yes
JSON
Yes
Released
2026-09-28

Call it from Geek Hub

Same OpenAI SDK. Change the base URL and the model id.

curl https://api.geekhub.mx/v1/chat/completions \
  -H "Authorization: Bearer $GEEKHUB_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic/claude-sonnet-5.5",
    "messages": [{"role": "user", "content": "Hola"}]
  }'
Get an API key

Frequently asked questions

What is Claude Sonnet 5.5?
Claude Sonnet 5.5 is Anthropic's Sonnet-class model for well-scoped everyday work, succeeding Claude Sonnet 5 as a direct upgrade. It is especially strong at building features, fixing bugs, and producing polished documents, slides, and spreadsheets, and it writes and communicates more clearly than its predecessor. Thinking is always on, so effort is the main lever for trading off depth, latency, and cost, and lower effort settings keep it responsive for everyday agentic loops. Claude Sonnet 5.5 runs on the Geek Hub API (OpenAI-compatible). Model id: anthropic/claude-sonnet-5.5.
Is Claude Sonnet 5.5 free?
No. Input is $2.1801 per 1M tokens and output is $10.9006 per 1M tokens on Geek Hub (markup included).
What is the context length of Claude Sonnet 5.5?
Claude Sonnet 5.5 has a 1M tokens context window. It supports up to 128,000 completion tokens.
Does Claude Sonnet 5.5 support tool calling and structured outputs?
Claude Sonnet 5.5 accepts tools and tool_choice for function calling. It also supports structured outputs via a JSON schema in response_format.
When was Claude Sonnet 5.5 released?
Claude Sonnet 5.5 was released on 2026-09-28.

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