Use Claude Code skills with OpenAI Codex

OpenAI's Codex (the 2026 incarnation — different from the deprecated 2021-2023 product) is a CLI + IDE agent that reads AGENTS.md as its primary rule file. AGENTS.md was adopted as the open Agentic AI Foundation standard in 2026 and is now read by Codex, Cursor (Agent mode), Windsurf, Gemini CLI, GitHub Copilot, and others. Mapping a ClaudSkills SKILL.md to AGENTS.md is essentially a rename.

Codex rule-file format (2026)

Codex looks for AGENTS.md in the project root and walks up the directory tree to layer instructions. In your Codex home directory, AGENTS.override.md takes precedence if present. Codex's config is TOML (~/.codex/config.toml), not JSON. As of May 2026, Codex's Goal mode runs autonomous multi-day objectives — skills that frame multi-step workflows are particularly useful here.

Modern (2026)	Legacy fallback
AGENTS.md (project root)	AGENTS.override.md (per-directory override in Codex home)

Upstream docs: https://developers.openai.com/codex/guides/agents-md

SKILL.md → Codex field mapping

SKILL.md field	Codex equivalent
name	→ no equivalent; just use the filename / H1
description	→ first paragraph of AGENTS.md
allowed-tools	→ Codex reads OS permissions; no per-rule tool list
user-invokable	→ AGENTS.md is always loaded

Worked example

Pick any ClaudSkills SKILL.md from the catalog. Strip the YAML frontmatter; drop the body into the file shown below:

# File: AGENTS.md

# Project assistant instructions

When working in this repo, follow these conventions:
- Branch from main, PR within 24h, never push to main directly
- All tests must pass before merge
- Use the language-specific style guide in docs/STYLE.md

Save, restart your editor session, and the skill becomes available to Codex's agent on the next prompt.

Recommended skills for Codex users

From the 6 skills below, pick the one or two that match your project's most-common workflows. Each links to the full SKILL.md on ClaudSkills.

• goal Quest objectives that drive narrative — the WANTS of adventure
• deploy-checklist Pre-deployment verification checklist. Use when about to ship a release, deploying a change with database migrations or feature flags, verifying CI status and approvals before goin
• incident-response Run an incident response workflow — triage, communicate, and write postmortem. Trigger with "we have an incident", "production is down", an alert that needs severity assessment, a
• tech-debt Identify, categorize, and prioritize technical debt. Trigger with "tech debt", "technical debt audit", "what should we refactor", "code health", or when the user asks about code qu
• documentation Documentation generation workflow covering API docs, architecture docs, README files, code comments, and technical writing.
• code-reviewer Comprehensive code review skill for TypeScript, JavaScript, Python, Swift, Kotlin, Go. Includes automated code analysis, best practice checking, security scanning, and review check

Limitations to know about

• AGENTS.md is a single file per directory. For multi-skill setups, layer files up the directory tree — Codex concatenates AGENTS.md from each parent directory.
• Codex Goal mode runs long-horizon objectives autonomously. Skills with explicit step ordering work well here; skills that depend on rapid back-and-forth approval work less well.
• AGENTS.md has no equivalent to SKILL.md's user-invokable: false on-demand loading — every line in AGENTS.md is always in context for Codex.

FAQ

Is AGENTS.md going to replace SKILL.md?

Not in Claude Code itself — Claude Code still uses SKILL.md as its primary skill format. But for cross-tool portability, AGENTS.md is the lingua franca of 2026. Most skills work in both formats with a frontmatter strip.

Does Codex support all 69,000+ ClaudSkills skills?

Most port cleanly. The biggest gap is Claude-specific tool-use idioms (XML tags around tool calls, Claude's specific refusal language). Codex uses OpenAI's tool-use format internally, so heavy Claude-specific wording may behave slightly differently.

Can I use AGENTS.override.md to share skills across projects?

Yes. Put your global / cross-project skills in ~/.codex/AGENTS.override.md; Codex layers them under every project's AGENTS.md. Same shape as Claude Code's ~/.claude/skills/ directory.

Keep reading

• All integrations — the full landscape across Cursor, Cline, Roo, Windsurf, Codex, Continue
• Claude Code skill catalogs compared — 5 catalogs head-to-head
• How to write a Claude Code skill
• SKILL.md frontmatter reference
• Browse 69,000+ skills