{
  "id": 8334588,
  "title": "Anthropic decides to support OpenAI's markdown instructions spec",
  "url": "https://urgent.news/2026/09/18/anthropic-decides-to-support-openais-markdown-instructions-spec-8334588",
  "topic": "ai",
  "section": "AI",
  "published": "2026-09-18T21:33:16.000Z",
  "source": {
    "name": "The Register",
    "slug": "the-register",
    "url": "https://www.theregister.com/ai-and-ml/2026/09/18/anthropic-decides-to-support-openais-markdown-instructions-spec/5297588"
  },
  "original_language": "en",
  "account": "Anthropic announced on Friday that it will now support OpenAI's AGENTS.md standard for providing instructions to AI agents. This development comes as a surprise to the developer community. Thariq Shihipar, an engineer at Claude Code, revealed the news in a social media post. Starting with version 2.1.277, Claude Code will automatically utilize AGENTS.md if it cannot find CLAUDE.md. Users can modify this behavior using the /config command. Previously, developers who utilized both Claude Code and OpenAI Codex had to maintain separate Markdown instructions for each platform. The CLAUDE.md and AGENTS.md files, which guide AI agents' behavior and preferences, were often out of sync. Anthropic's decision to support AGENTS.md follows OpenAI's contribution of the same standard to the Agentic AI Foundation last year. Over 60,000 open source projects have already adopted AGENTS.md. This move is significant for users of AI coding tools, although its impact may be modest given the existing popularity of Claude Code. OpenAI's CEO expressed enthusiasm about the development, confirming the arrangement through a handshake emoji.",
  "summary": "Devs cheer relief from compatibility headache",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 2,
    "also_reported_by": [
      {
        "outlet": "The Register Science",
        "title": "Anthropic decides to support OpenAI's markdown instructions spec",
        "url": "https://urgent.news/2026/09/18/anthropic-decides-to-support-openais-markdown-instructions-spec",
        "published": "2026-09-18T21:33:16.000Z"
      }
    ]
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}