OpenAI launches Agents API in public beta

On September 10, 2026, OpenAI opened its Agents API in public beta — a managed runtime for long-running agents with files, code execution, tools, MCP and parallel subagents. The infrastructure comes from its internal Codex harness.

• Agents API entered public beta on September 10, 2026
• Supports files, code execution, web search, MCP and custom functions
• Subagents run in parallel, each with its own context
• OpenAI warns it is beta; reliability and cost need testing