OpenAI unveils Decisions API for fast, constrained AI choices

OpenAI wants some of its models to talk less and decide more. At DevDay 2026 on September 29, the company introduced the Decisions API, a tool built for quick, inexpensive choices rather than long-form answers. Picture a multiple-choice exam for AI. The developer writes the options, and the model circles one. How the Decisions API works The engine is a specialized version of GPT-6 Luna. Instead of generating open-ended responses, it returns a single answer from a finite set of options that the user defines ahead of time. The API accepts both text and image context. That means a developer can feed it a screenshot, a photo or a block of text and ask it to sort the input into a predefined bucket. OpenAI pointed to several practical jobs for the tool. These include content classification, routing incoming requests such as support tickets, and choosing the next action an AI agent should take. Speed is the standout number. Early demonstrations showed end-to-end response times of around 150 milliseconds, compared with ~1.6 seconds for standard Luna calls. That works out to a latency improvement of approximately 10 times. For an agent chaining many small decisions together, those seconds s...