GPT-5.6 Sol
⧉GPT-5.6 Sol is the frontier flagship of the GPT-5.6 family, built for the most demanding agentic coding, deep reasoning and research-grade tasks. Fully OpenAI-SDK compatible: plug it into Codex, Cursor, Claude Code and similar tools with zero code changes.
Live Test · Playground
Try out GPT-5.6 Sol right here (available after login).
Input
Advanced
The upstream for this model does not accept temperature / top_p / max_tokens (they are silently ignored). Use reasoning_effort below for thinking depth, and prompt wording for length.
Conversation
About GPT-5.6 Sol
GPT-5.6 Sol is the frontier flagship of the GPT-5.6 family, built for the most demanding agentic coding, deep reasoning and research-grade tasks. Fully OpenAI-SDK compatible with streaming and reasoning_effort control; plug it into Codex, Cursor or Claude Code by setting model to gpt-5.6-sol. Pay-as-you-go, failed calls never billed.
Use cases
Cross-file refactors, long-horizon tasks and automated engineering flows: pick it when you need the strongest reasoning.
Multi-step reasoning, long-document analysis and complex decisions; pair it with reasoning_effort=high for deeper thinking.
OpenAI-compatible tools / JSON output shapes, so existing workflows run unchanged.
How to choose
Within the family Sol is the strongest, Terra the balanced one and Luna the cheapest: Terra for daily development, Luna for high-volume low-latency work, Sol only for the hardest tasks.
FAQ
Sol or gpt-5.5?
Does it support reasoning_effort?
How large is the context window?
Am I charged for failed calls?
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