OpenAI's Decisions API for fast structured decisions becomes generally available with GPT-6 Luna

Archive entry: this covers an event from October 22, 2026, and we published it on November 8, 2026. The details come from sources dated at the time and may have changed since.

On October 22, 2026, OpenAI made the Decisions API generally available on gpt-6-luna, according to OpenAI's announcement. The API had launched in beta on October 6, when OpenAI described it as 10x faster than the Responses API.

What changed at general availability

• Prompt-cache discounts were added.
• Question instructions can include images.
• input_json support was added.
• A request can contain up to 400 questions, up from 200 in the beta.
• On October 15, OpenAI added a Decisions integration in GPT-Live.

What it means for people building with AI

Classification and routing calls that sit in the hot path of an app are the use case this endpoint targets. At general availability they can use an endpoint built for decisions, which OpenAI described in beta as 10x faster than the Responses API and which gained prompt-cache discounts and a limit of 400 questions per request, up from 200.

Microsoft Foundry and sources

Microsoft Foundry also made the Decisions API generally available on October 22, 2026, with predicate, choice and score question types on gpt-6-luna, as listed in Microsoft Foundry's October 2026 roundup. OpenAI's API changelog also records the general availability.

Sources

• Build more responsive apps with the Decisions API (OpenAI, October 22, 2026, official)
• OpenAI API changelog: Decisions API general availability (OpenAI, October 22, 2026, official)
• OpenAI News RSS feed (item: Build more responsive apps with the Decisions API) (OpenAI, October 22, 2026, official)
• What's new in Microsoft Foundry | October 2026 (Microsoft, November 5, 2026, official)

Written with AI assistance, strictly from the sources listed above. Before it went live, automated checks verified its dates, sources and every language edition.