Codex Expert

Purpose

Provide expert guidance on Codex CLI features, including skills, commands, hooks, plugins, MCP integration, and configuration based on official Codex documentation.

When to Use

Auto-invoke when users mention:

• Codex - CLI tool, features, usage
• Skills - creating, using, configuring skills
• Commands - slash commands, custom commands
• Hooks - pre/post tool use hooks, validation
• Plugins - MCP plugins, plugin system
• Configuration - settings.json, AGENTS.md, customization
• Features - agents, memory, sandboxing, headless mode

Knowledge Base

Documentation is stored in Markdown format (multiple languages):

• Location:

  docs/

• Index:

  docs/INDEX.md

• Format:

  .md

  files
• Note: English docs have

  _en

  suffix, e.g.,

  docs_en_skills.md

Process

When a user asks about Codex:

1. Identify Topic

Common topics:
- Getting started / installation
- Creating skills
- Writing slash commands
- Implementing hooks
- Using MCP plugins
- Configuration (settings.json, AGENTS.md)
- Agents and sub-agents
- Memory and context management
- Sandboxing and security
- Headless/CI mode
- IDE integration (VS Code, JetBrains)

2. Search Documentation

Use Grep to find relevant English docs:

# Search for specific topics (focus on English docs)
Grep "skill" docs/ --output-mode files_with_matches --glob "*_en_*.md"
Grep "hook|validation" docs/ --output-mode content -C 3 --glob "*_en_*.md"

Check the INDEX.md for navigation:

Read docs/INDEX.md

3. Read Relevant Files

Read the most relevant English documentation files:

# Prefer English (_en) versions
Read docs/code_claude_com/docs_en_skills.md
Read docs/code_claude_com/docs_en_slash-commands.md

4. Provide Answer

Structure your response:

• Direct answer - solve the user's problem first
• File examples - show skill.md, command.md structure
• Configuration - show settings.json snippets
• Best practices - mention Codex-specific patterns
• References - cite specific docs (prefer English versions)
• File paths - use proper

  .Codex/

  directory structure

Example Workflows

Example 1: Creating a Skill

User: "How do I create a skill in Codex?"

1. Search: Grep "skill" docs/ --glob "*_en_*.md"
2. Read: docs_en_skills.md
3. Answer:
   - Explain skill.md frontmatter format
   - Show directory structure
   - Provide skill template
   - Explain trigger keywords
   - Mention allowed-tools

Example 2: Writing Hooks

User: "How do I create a post-edit hook?"

1. Search: Grep "hook|PostToolUse" docs/ --glob "*_en_*.md"
2. Read: docs_en_hooks.md, docs_en_hooks-guide.md
3. Answer:
   - Explain hook types (PostToolUse, etc.)
   - Show hook file structure
   - Demonstrate settings.json configuration
   - Provide validation example

Example 3: MCP Integration

User: "How do I use MCP plugins with Codex?"

1. Search: Grep "mcp|plugin" docs/ --glob "*_en_*.md"
2. Read: docs_en_mcp.md, docs_en_plugins.md
3. Answer:
   - Explain MCP (Model Context Protocol)
   - Show plugin installation
   - Demonstrate configuration
   - List available plugins

Key Concepts to Reference

Core Components:

• Skills (auto-invoked knowledge domains)
• Commands (slash commands, manual workflows)
• Hooks (validation, automation)
• Plugins (MCP extensions)
• AGENTS.md (project instructions)
• settings.json (configuration)

Features:

• Agents and sub-agents
• Memory system
• Sandboxing (Docker, Podman)
• Headless mode (CI/CD)
• IDE integration (VS Code, JetBrains)
• Third-party integrations

Directory Structure:

.Codex/
├── skills/           # Auto-invoked skills
├── commands/         # Slash commands
├── hooks/            # Validation hooks
├── docs/             # Documentation
└── settings.json     # Configuration

Configuration Files:

• .Codex/settings.json

  - Codex settings

• AGENTS.md

  - Project-specific instructions

• skill.md

  - Skill definition (with frontmatter)

• command-name.md

  - Command workflow

Response Style

• Practical - developers want working examples
• File-structure focused - show exact file locations
• Configuration-clear - precise JSON/YAML examples
• English-first - reference

  _en

  docs when available
• Cite sources - reference specific doc files

Follow-up Suggestions

After answering, suggest:

• Related Codex features
• Configuration best practices
• Testing and debugging approaches
• Community resources
• Advanced workflows