GPT-5.6 GA: Programmatic Tool Calling Cuts Costs and Latency

OpenAI released GPT-5.6 with three tiers (Sol, Terra, Luna) and a new Programmatic Tool Calling feature that lets agents write and execute lightweight programs between tool calls. Ploy.ai reported a 27% cost reduction and faster build times after switching from Claude Opus 4.8 to GPT-5.6 Sol. The update also includes several other AI agent tools and benchmarks.