/codex

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Codex Integration for Claude Code

Purpose

Enable Claude Code to invoke the Codex CLI (codex exec and session resumes) for automated code analysis, refactoring, and editing workflows.

Prerequisites

• codex CLI installed and available on PATH.
• Codex configured with valid credentials and settings.
• Confirm the installation by running codex --version; resolve any errors before using the skill.

Installation

Download this repo and store the skill in ~/.claude/skills/codex

git clone --depth 1 git@github.com:skills-directory/skill-codex.git /tmp/skills-temp && \
mkdir -p ~/.claude/skills && \
cp -r /tmp/skills-temp/ ~/.claude/skills/codex && \
rm -rf /tmp/skills-temp

Usage

Important: Thinking Tokens

By default, this skill suppresses thinking tokens (stderr output) using 2>/dev/null to avoid bloating Claude Code's context window. If you want to see the thinking tokens for debugging or insight into Codex's reasoning process, explicitly ask Claude to show them.

Example Workflow

User prompt:

Use codex to analyze this repository and suggest improvements for my claude code skill.

Claude Code response: Claude will activate the Codex skill and:

1. Ask which model to use (gpt-5 or gpt-5-codex) unless already specified in your prompt.
2. Ask which reasoning effort level (low, medium, or high) unless already specified in your prompt.
3. Select appropriate sandbox mode (defaults to read-only for analysis)
4. Run a command like:

codex exec -m gpt-5-codex \
  --config model_reasoning_effort="high" \
  --sandbox read-only \
  --full-auto \
  --skip-git-repo-check \
  "Analyze this Claude Code skill repository comprehensively..." 2>/dev/null

Result: Claude will summarize the Codex analysis output, highlighting key suggestions and asking if you'd like to continue with follow-up actions.

Detailed Instructions

See SKILL.md for complete operational instructions, CLI options, and workflow guidance.