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OpenAI · Language model

GPT-5.6 Terra

openai/gpt-5.6-terra
  • Language
Released Jul 9, 2026

GPT-5.6 Terra is a balanced model in OpenAI's GPT-5.6 series, positioned between the flagship Sol tier and the cost-efficient Luna tier. It is suited for everyday coding, reasoning, and agentic...

Specifications

Context window
1,050,000 tokens
Max output
128,000 tokens
Input
file, image, text
Output
text
Reasoning effort
max, xhigh, high, medium, low, none
Tokenizer
GPT
Knowledge cutoff
2026-02-16
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
  • 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-5.6-terra","messages":[{"role":"user","content":"Hello"}],"max_tokens":300}'