GPT-5.6 Sol
OpenAI's flagship GPT-5.6 tier for frontier reasoning and long-horizon agentic work. Sets a Terminal-Bench 2.1 state of the art (91.9% in Ultra mode). Introduces a max reasoning-effort control and an Ultra multi-agent mode that coordinates parallel sub-agents. 1.05M-token context window.
Specifications
| Lab | OpenAI |
|---|---|
| Context window | 1.1M tokens |
| Input price | $2.00/1M |
| Output price | $10.00/1M |
| Release | Jul 2026 |
Strengths
- Terminal-Bench 2.1 SOTA (91.9% in Ultra mode)
- Ultra multi-agent mode coordinates parallel sub-agents for complex tasks
- 1.05M-token context for long-horizon agentic work
- Max reasoning-effort control for deeper single-pass reasoning
- New predictable prompt-caching with explicit cache controls
Weaknesses
- Highest GPT-5.6 price at $5/$30 per 1M tokens
- Ultra mode multiplies token spend via parallel sub-agents
- Limited preview access at launch; GA rolling out
Best for
- Frontier agentic coding and tool use
- Long-horizon automation and research
- Deep reasoning and hard multi-step problems
In Depth: GPT-5.6 Sol
Summary
GPT-5.6 Sol is an AI model from OpenAI.
Released in Jul 2026. It takes text input and produces text output, with a context window of 1.1M tokens. Input pricing is $2.00 per 1M tokens and output is $10.00 per 1M tokens on OpenRouter.