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Anthropic · Language model

Claude Sonnet 5.5

anthropic/claude-sonnet-5.5
  • Language
Released Sep 28, 2026

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...

Specifications

Context window
1,000,000 tokens
Max output
128,000 tokens
Input
text, image, file
Output
text
Reasoning effort
max, xhigh, high, medium, low (always on)
Tokenizer
Claude
Moderation
provider-moderated

Supported parameters

Accepted by the model and forwarded as-is by the gateway.

  • max_completion_tokens
  • max_tokens
  • reasoning
  • reasoning_effort
  • response_format
  • stop
  • structured_outputs
  • temperature
  • tool_choice
  • tools
  • verbosity

Use it

POST /api/v1/chat/completions · MCP chat · full reference

curl https://omnirail.org/api/v1/chat/completions \
  -H "Authorization: Bearer $OMNIRAIL_KEY" -H "Content-Type: application/json" \
  -d '{"model":"anthropic/claude-sonnet-5.5","messages":[{"role":"user","content":"Hello"}],"max_tokens":300}'