OpenAI launches Agents API in public beta: Codex harness as a cloud agent service
minchoi · x · 2026-09-12
OpenAI released its Agents API in public beta, exposing the Codex harness as a managed API for all developers, with OpenAI handling orchestration, long-running sessions, and context management.
Key capabilities:
- One call to spin up a cloud agent; long-running sessions
- Automatic context compaction, working across multiple context windows
- Parallel subagents that can delegate work
- MCP + built-in tools, operating across files and running code
- OpenAI-hosted sandboxes, or run on your own infra
There's no extra Agents API fee — you pay only for the models and tools your agent uses. Developers supply a task, model, tools, and environment; OpenAI effectively opens up Codex infrastructure to all agent builders.
Related event: OpenAI Launches Agents API Public Beta, Opening Up the Codex Harness(21 posts)→
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