AGENTS.md is a real standard, not a rebrand
AGENTS.md was formalized as an open specification in August 2025 through a collaboration led by OpenAI with Google, Cursor, and Factory participating, then donated in December 2025 to the Linux Foundation's Agentic AI Foundation. It has no required fields or fixed schema — it's plain Markdown, typically covering build/test commands, code style, and testing instructions, read by whatever headings a repository actually uses. That openness is the point: it's meant to be one file many tools can read, instead of one per vendor.
Codex reads AGENTS.md natively, consistent with OpenAI's role in creating the spec. That's the clean case. The other two hosts most teams care about are messier, and getting this wrong means half your instructions silently go unread.
Claude Code does not read AGENTS.md
As of mid-2026, Claude Code reads CLAUDE.md and does not read AGENTS.md, despite AGENTS.md's broad adoption elsewhere. This is Claude Code's most-requested unresolved feature request. Two documented workarounds exist if you want a single source file: symlink it (ln -s AGENTS.md CLAUDE.md) so both filenames point at the same content, or add a one-line @AGENTS.md import at the top of a short CLAUDE.md. Either avoids maintaining two diverging files by hand.
Veomark's own CLAUDE.md starter and AGENTS.md starter are separate downloads for exactly this reason: copying an AGENTS.md file into a project and assuming Claude Code will pick it up will not work without one of the two steps above.
Gemini CLI, GEMINI.md, and Antigravity
Google replaced the free/Google One tier of Gemini CLI with a new product, Antigravity CLI, on June 18, 2026 — Gemini CLI's own documentation carries a notice to that effect. The Gemini CLI GitHub repository itself shows no deprecation notice and continues active development, so this is a tier change for individual/free users rather than the project being discontinued outright; check current status before assuming which product your users are on.
Both context mechanisms remain configurable: Gemini CLI supports a context.fileName setting in settings.json that can list multiple filenames — for example ["AGENTS.md", "GEMINI.md"] — so a project can point Gemini CLI at the same AGENTS.md used elsewhere instead of maintaining a separate GEMINI.md. Antigravity, Google's replacement for most consumer users, is documented to read AGENTS.md directly.
A practical setup for one project
Write one AGENTS.md at the repository root as the source of truth — it is the format Codex, Antigravity, and (per its own docs) Gemini CLI can all read without extra configuration. For Claude Code, either symlink CLAUDE.md to it or keep a short CLAUDE.md that starts with @AGENTS.md plus any Claude-specific additions (which tools it's allowed to run without confirmation, for instance). For Gemini CLI specifically, set context.fileName in its settings if you want it to read the same AGENTS.md instead of a separate GEMINI.md.
This only covers project-level instructions, not skills. A SKILL.md is a different, more specific mechanism — a self-contained capability with its own frontmatter, loaded only when relevant — and the two are meant to complement each other, not replace one another.
Frequently asked questions
Will Claude Code ever read AGENTS.md natively?
Unknown — it is an open, heavily-upvoted feature request as of this review, not a shipped feature. Until it ships, use the symlink or @AGENTS.md-import workaround if you want one file to serve both Claude Code and AGENTS.md-native tools.
Is Gemini CLI shut down?
No — its GitHub repository shows active, ongoing development. What changed is that the free/Google One consumer tier was replaced by a new product, Antigravity CLI, on June 18, 2026, per Gemini CLI's own documentation. Confirm which tier your intended users are actually on before deciding where to invest GEMINI.md effort.
Do Kimi Code CLI or Grok Build read AGENTS.md?
We have not independently verified AGENTS.md support for Kimi Code CLI or Grok Build specifically as part of this review — check each host's current documentation rather than assuming. This guide only makes claims we checked against Codex, Claude Code, and Gemini CLI/Antigravity's own current documentation.
Should I just maintain three separate files?
You can, and some teams prefer explicit per-host files over symlinks. The tradeoff is drift: three files maintained by hand will diverge. A single AGENTS.md plus the Claude Code workaround keeps one source of truth if that matters more to your team than host-specific wording.
Sources checked for this guide
- AGENTS.md — official specification site
- AGENTS.md — agentsmd/agents.md on GitHub
- Gemini CLI documentation (Antigravity replacement notice)
- Provide context with GEMINI.md files — Gemini CLI docs
Verified against the sources above as of 2026-09-18. Vendor documentation and product availability can change after that date — check the current source before relying on a specific command or claim.
Related resources
- AGENTS.md project starterDownload an AGENTS.md starter for Codex with project commands, conventions and work boundaries. Customize it for your repository.
- CLAUDE.md project starterGive Claude Code durable project context with an editable CLAUDE.md starter for commands, conventions and relevant references.
- GEMINI.md project starterDownload a GEMINI.md starter to describe your project, commands and constraints to Gemini CLI. Merge it with existing instructions.