OpenAI's new Agents API gives developers the infrastructure behind Codex and ChatGPT
OpenAI released its Agents API in public beta, exposing the infrastructure behind Codex and ChatGPT for building long-running cloud agents.
OpenAI launched the Agents API as a public beta, letting developers build cloud-based agents that can run for hours, execute code, and process files on the same infrastructure that powers Codex and ChatGPT. Features include automatic context management, parallel tool use, and task delegation to sub-agents, with a choice of OpenAI-hosted sandboxes or partner environments from Cloudflare, Vercel, and Oracle. The API builds on the open-source Codex harness and supports MCP, custom functions, and built-in tools such as web search, with no extra fees beyond token-based billing.
Introducing the Agents API
OpenAI launched the Agents API in public beta, exposing the Codex agent harness, managed sandboxes, and multi-agent orchestration to developers.
OpenAI introduced the Agents API in public beta, giving developers the same agent harness and infrastructure that powers Codex through a single API call specifying task, model, tools, and environment. It supports OpenAI-managed sandboxes, customer infrastructure, or partner environments from providers including Cloudflare, Modal, E2B, Vercel, Oracle, DigitalOcean, Blaxel, Daytona and Runloop. Features include automatic context compaction for long sessions, tool search and programmatic tool calling to reduce token usage, and multi-agent support for parallel subagents. The harness is open-source Codex code; there are no extra API fees during beta, with developers paying only for tokens and tools used.
OpenAI Agents API
OpenAI's Agents API documentation describes a managed Codex harness offering sandboxed agents, MCP connectivity, subagents, and US-only data residency.
The Agents API lets applications run durable agent sessions while OpenAI manages orchestration, context compaction, and recovery on the Codex harness. Agents can execute code, edit files, and connect to MCP servers in OpenAI-hosted or self-hosted sandboxes. Example applications include an incident response agent, Slack bot, data analyst, and GitHub issue investigator. Billing follows model, tool, and container rates; the examples use model gpt-6-astra.
OpenAI Launches the Agents API in Public Beta, Putting the Codex Harness Behind One API Call
OpenAI released its Agents API in public beta, exposing the managed Codex harness with hosted or self-hosted sandboxes, MCP tools, and subagents.
The Agents API is a managed service built on the open-source Codex harness, handling context compaction, tool search, programmatic tool calling, and multi-agent orchestration. Agents run in OpenAI-hosted sandboxes, self-hosted environments, or partner sandboxes from Blaxel, Cloudflare, Daytona, DigitalOcean, E2B, Modal, Oracle, Runloop, and Vercel. Data residency is US-only and Zero Data Retention is unsupported. Examples use model gpt-6-astra; vendor-reported results include SafetyKit cutting case review cost 60% and Ciridae achieving 4x lower subagent latency.
The VMs Powering Mobile Agents (Instinct, Claude Code)
A teardown reveals Claude Code runs in Firecracker microVMs with a Rust PID 1 and MITM'd egress, while Instinct rents E2B sandboxes with git-based memory.
The author inspects the virtual machines hosting cloud agents: Claude Code runs in a Firecracker microVM with a custom Rust init (process_api) as PID 1, a 324 MB Bun harness on a read-only disk, and 443-only MITM'd SSE egress to api.anthropic.com with host-rotated OAuth tokens and no inbound access. Instinct rents E2B sandbox-as-a-service Firecracker microVMs (Ubuntu 22.04, 2 vCPU, 1.9 GB RAM) where agent memory is a git repo of Markdown committed by the agent and pushed to S3 as a single bundle, using short-lived STS credentials. Both platforms rely on Firecracker, differing mainly in fleet operator and guest boot configuration.
Ask HN: How do you manage skills files?
A Hacker News thread debates whether agent skill files are worth managing, citing 2–4x output-token reductions on flagship models in one company's testing.
Commenters argue skills are stored prompts that help less-technical users compensate for weak prompting, while one participant reports company testing found skills reduce flagship-model output tokens by roughly 2–4x, a gap growing with newer models. Others note skills can bundle reusable scripts and inline commands for deterministic context building, and that harnesses now execute backticked commands before the agent sees the skill. Some argue improving model capability makes downloadable skills redundant.