OpenAI opens the Agents API beta: the Codex harness as a managed service

OpenAI put the Agents API into public beta for all developers: a managed service powered by the Codex harness (open-source codebase) where OpenAI runs session orchestration, context compaction and recovery. One API call takes a task, a model, tools and an environment; compute can be OpenAI-managed sandboxes, the customer's own infrastructure via a proxy, or sandbox partners (Blaxel, Cloudflare, Daytona, DigitalOcean, E2B, Modal, Oracle, Runloop, Vercel). Agents persist across turns with streaming progress, call MCP servers / custom functions / built-in web search, and 'auto compaction' carries notes across context windows; tool search discovers MCP tools without loading every schema; programmatic tool calling reads tool outputs mid-chain; subagents run in parallel with their own contexts. No additional fees during beta beyond token and tool usage.

The harness — orchestration, compaction, sandboxing, recovery — is now a product surface rather than something every team rebuilds. The own-infrastructure option makes the execution plane a real procurement axis (vendor sandbox vs your cloud vs partners), and the open-source harness plus managed twin removes the lock-in argument that usually blocks adoption. Expect the internal 'agent loop' layer of many stacks to be re-evaluated against this.