The builder’s guide to GPT‑5.6 Technical lessons from startups in production The GPT‑5.6 model family makes frontier-level agent performance dramatically more affordable, while also advancing the frontier of what is possible. In this guide, we show how startups are using smarter model selection and new API controls that help with reasoning continuity, multi-agent orchestration, and programmatic tool calling to build faster, more capable agents at a fraction of the cost. Since GPT‑5, each model generation has sought to tackle longer-horizon tasks with fewer tokens. GPT‑5.6 continues that trajec