{"rewrite":{"id":"r_3e61b666d1dd7cde1849b6be","clusterId":"c_60a9ee47e44d8e33f939ce4b","slug":"openai-opens-agents-api-beta-lets-developers-build-on-codex-harness","model":"deepseek-v4-flash","headline":"OpenAI Opens Agents API Beta, Lets Developers Build on Codex Harness","summary":"OpenAI released the public beta of its Agents API, aimed at developers building internal or customer-only AI agents. A harness that handles prompt formatting, tool use, context management and long-running sessions is required for agent work, and the Agents API lets developers use the same harness as Codex instead of maintaining their own. Tool calls run in a sandbox, either OpenAI-hosted or self-hosted through providers including Oracle and Cloudflare.","whyItMatters":"OpenAI is selling the harness layer that most agent builders currently maintain themselves, and the self-hosted sandbox path through Oracle and Cloudflare tells developers where in the stack OpenAI is willing to let third parties stay.","webCardHtml":"\u003cp\u003eThe Agents API runs the loop an agent needs: it reads the input, executes tool calls, runs the processing inside a sandbox, and returns results. Sandboxes come in two forms. Developers can use OpenAI-hosted sandboxes or self-hosted ones supplied by providers such as Oracle and Cloudflare.\u003c/p\u003e\u003cp\u003eUsing the API itself costs nothing. Model usage through the API is billed per model. A quickstart guide covers the first build.\u003c/p\u003e","blueskyPost":"OpenAI's Agents API public beta lets developers build AI agents on the same harness as Codex, with tool calls run in OpenAI-hosted or self-hosted sandboxes from providers like Oracle and Cloudflare. The API is free to use; model calls are billed per model.","twitterPost":"OpenAI opened the Agents API public beta. Developers can build AI agents on the same harness as Codex, with tool calls sandboxed either on OpenAI infrastructure or self-hosted via Oracle and Cloudflare. API use is free; model usage is billed.","threadsPost":null,"newsletterBlurb":"OpenAI released the public beta of its Agents API, which lets developers build AI agents on the same harness as Codex rather than maintaining prompt formatting, tool use, context and session management themselves. Tool calls run in a sandbox, either OpenAI-hosted or self-hosted through providers including Oracle and Cloudflare. The API is free to use, with model usage billed per model.","attributionJson":"[{\"source\":\"GIGAZINE\",\"url\":\"https://gigazine.net/news/20260911-openai-agents-api/\",\"title\":\"Agents API launches, allowing AI agents to be built using the same harness as Codex\"}]","lintFlagsJson":null,"lintHits":0,"costUsd":0,"inputTokens":4655,"outputTokens":551,"status":"published","repairAttempts":0,"nextRepairAt":null,"factsAttemptedAt":1789100081,"createdAt":"2026-09-11T04:10:44.000Z","publishedAt":"2026-09-11T04:13:25.000Z","updatedAt":"2026-09-11T04:13:25.000Z"},"cluster":{"id":"c_60a9ee47e44d8e33f939ce4b","canonicalTitle":"Codexと同じハーネスを使ってAIエージェントを作れる「Agents API」が登場","representativeArticleId":"a_29ab29e767c71c5bb11fce61","sourceCount":1,"writtenSourceCount":1,"writeAttempts":0,"isSolo":true,"entitiesJson":"{\"anime_titles\":[],\"manga_titles\":[],\"work_titles\":[],\"studios\":[\"OpenAI\"],\"people\":[],\"type\":\"release\",\"domain\":\"other\",\"is_roundup\":false}","contentType":"news","status":"published","firstSeenAt":"2026-09-11T03:10:00.000Z","lastSeenAt":"2026-09-11T03:10:00.000Z","updatedAt":"2026-09-11T04:13:21.000Z"},"attribution":[{"source":"GIGAZINE","url":"https://gigazine.net/news/20260911-openai-agents-api/","title":"Codexと同じハーネスを使ってAIエージェントを作れる「Agents API」が登場"}],"entities":{"anime_titles":[],"manga_titles":[],"work_titles":[],"studios":["OpenAI"],"people":[],"type":"release","domain":"other","is_roundup":false},"keyFacts":null}