Documentation: Reference Agent Rules Community Standard for AGENTS.md to Promote Interoperability

Resolved 💬 7 comments Opened Jul 19, 2025 by sgryphon Closed Oct 19, 2025
💡 Likely answer: A maintainer (tibo-openai, collaborator) responded on this thread — see the highlighted reply below.

What is the type of issue?

Something else

What is the issue?

Codex CLI's use of AGENTS.md as a generic, tool-agnostic file for natural language guidelines (rather than a Codex-specific name) is forward-thinking and has inspired the creation of the Agent Rules specification—a minimalist community standard aimed at unifying configs across AI coding agents like Cline, Aider, Cursor, and GitHub Copilot. This reduces fragmentation, allowing developers to define rules once for cross-tool compatibility, similar to how EditorConfig standardized editor settings.

To build on this, I suggest updating the documentation to:

  • Explicitly state that Codex conforms to the Agent Rules v1.0 specification (it already meets the core requirements: checking for AGENTS.md in the project root, parsing as natural language in Markdown/plain text, and including in context without extra structure).
  • Add a link to https://agent-rules.org/ for more on the standard and its benefits.

This would position Codex as a leader in ecosystem interoperability without any code changes, encouraging broader adoption and benefiting users who mix agents.

Where did you find it?

The AGENTS.md feature is referenced in the README.md under the "Memory & project docs" section, where it describes how Codex loads and merges AGENTS.md files from various locations (global, repo root, and current directory) to provide extra instructions.

Suggested update: In that section, after the description of file locations and merging, add a paragraph like: "Codex's support for AGENTS.md conforms to the Agent Rules v1.0 community standard, enabling interoperability with other AI coding agents. For details on the standard and examples, see https://agent-rules.org/."

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7 Comments

reloxx13 · 12 months ago

This issue and links is so helpfull, thankyou. Readme lacks on agents.md informations. I didnt know the agents-rules.

sgryphon · 12 months ago
This issue and links is so helpfull, thankyou. Readme lacks on agents.md informations. I didnt know the agents-rules.

It also looks like there will be a micro site set up at http://agents.md/ (because OpenAI has bought the domain), but it didn't exist / doesn't exist yet, so I set up agent-rules.org in the short term to start documenting the tools that use the standard.

drelias15 · 12 months ago

Looks like https://agent-rules.org/ is down.

imajes · 11 months ago

https://agent-rules.org is back. looks like there's also https://agentsmd.net too, not sure who owns that.

tibo-openai collaborator · 9 months ago

We have documented this under https://agents.md/ and it is now a standard across many other agentic coding tools.

Ar9av · 1 month ago

Data point for this discussion: agent-manual (https://github.com/Ar9av/agent-manual) documents how each agent actually loads these files today.

Current state across the major tools:

  • Claude Code reads CLAUDE.md recursively from the repo root up through all parent directories, loading all of them into context
  • Codex reads AGENTS.md from the nearest ancestor directory (no recursive parent loading)
  • Gemini CLI reads GEMINI.md at project scope; also picks up AGENTS.md as a compatibility alias
  • Aider reads CONVENTIONS.md or any file explicitly passed via --read; no auto-discovery
  • Cursor reads .cursor/rules/*.mdc with per-file glob matchers and alwaysApply flags

The markdown content format is already compatible across all of them. The divergence is in filename, loading scope (single file vs. recursive tree), and whether parent-directory files are merged or ignored. A cross-agent standard would need to pick a lane on at least those three.

sgryphon · 1 month ago

@Ar9av this item has been solved and closed in Jul last year (10 months ago). See http://agents.md/

Codex, Gemini, Aider, and Cursor (most of those you mention) all support AGENTS.md, along with 20 other tools and 60k open source repositories.

The main holdout is Claude, who are big enough to go their own way.