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OpenAI · Language model
GPT-5.5 Pro
openai/gpt-5.5-pro- Language
GPT-5.5 Pro is OpenAI’s high-capability model optimized for deep reasoning and accuracy on complex, high-stakes workloads. It features a 1M+ token context window (922K input, 128K output) with support for...
Specifications
- Context window
- 1,050,000 tokens
- Max output
- 128,000 tokens
- Input
- file, image, text
- Output
- text
- Reasoning effort
- xhigh, high, medium (always on)
- Tokenizer
- GPT
- Knowledge cutoff
- 2025-12-01
- Moderation
- provider-moderated
Supported parameters
Accepted by the model and forwarded as-is by the gateway.
- max_tokens
- reasoning
- reasoning_effort
- response_format
- seed
- structured_outputs
- tool_choice
- tools
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":"openai/gpt-5.5-pro","messages":[{"role":"user","content":"Hello"}],"max_tokens":300}'