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AI Playbook

Agent Skills

📖 2 min read openaiagent-skillscodexmcp
How OpenAI supports the SKILL.md agent skills standard — Codex skills, Agents SDK skills, portability across 32+ tools, and when to use skills vs MCP vs function calling.
Key Takeaways
  • OpenAI fully supports the SKILL.md open standard — same format as Anthropic's Agent Skills
  • Skills are portable across Codex, Claude Code, Cursor, Copilot, and 32+ other tools
  • Use Skills for repeatable workflows, MCP for live data, Function Calling for deterministic actions

This is an OpenAI-specific overview. For the complete deep-dive — including the SKILL.md format, skills vs tools vs MCP, sub-agent orchestration, and the full ecosystem — see Agent Skills — Full Deep Dive.

OpenAI’s SKILL.md Support

OpenAI adopted the SKILL.md open standard within 48 hours of Anthropic’s December 2025 release. Codex, the Agents SDK, and ChatGPT all read the same SKILL.md files from the same directory layout.

Terminal window
# Same format works across Codex, Claude Code, and Cursor
.codex/skills/         # Codex
.claude/skills/        # Claude Code
.cursor/skills/        # Cursor

Codex Skills

---
name: review-security
description: Audit code for OWASP Top 10 vulnerabilities
---


## Process
1. Scan changed files for common vulnerability patterns
2. For each finding, assess severity (Critical/High/Medium/Low)
3. Provide CWE reference and remediation code
4. Output as a GitHub issue with labels

Agents SDK Skills

from agents import Agent, Skill


agent = Agent(
    name="Security Auditor",
    model="gpt-5.4-mini",
    skills=[Skill.from_file(".codex/skills/review-security/SKILL.md")]
)

Portability

A skill written for Claude Code works in Codex and vice versa. The 32+ tools supporting SKILL.md include:

  • Codex, Claude Code, Cursor, GitHub Copilot, VS Code
  • Windsurf, Aider, JetBrains Junie, AWS Kiro, Amp
  • Google Gemini CLI, ChatGPT

Going Deeper

The full Agent Skills deep dive covers:

  • The complete SKILL.md format with all sections
  • Advanced examples with scripts and assets
  • Sub-agents and orchestration patterns
  • When to use skills vs MCP vs function calling