OpenAI Codex Plugin for Claude Code: Use Codex for Code Reviews and Task Delegation Without Leaving Your Workflow

If you're using Claude Code as your primary AI coding assistant, you've probably wondered: "What if I could get a second opinion from another AI model without switching tools?" The new OpenAI Codex Plugin for Claude Code answers that question by bringing Codex's code review and task delegation capabilities directly into your Claude Code workflow.

This isn't just another plugin — it's a bridge between two of the most powerful AI coding assistants, letting you leverage the strengths of both without context-switching or duplicating work.

What Is the Codex Plugin for Claude Code?

The Codex Plugin is an official OpenAI integration that adds slash commands to Claude Code, enabling you to:

• Run read-only code reviews on your uncommitted changes or branch diffs
• Perform adversarial reviews that challenge your design decisions and assumptions
• Delegate complex tasks like bug investigation and fixes to Codex's specialized models
• Transfer sessions between Claude Code and Codex seamlessly

The plugin works by wrapping the Codex app server and using your local Codex CLI installation, so it respects your existing authentication and configuration.

Key Commands and How to Use Them

/codex:review — Standard Code Review

The most straightforward command. It analyzes your current changes and provides detailed feedback:

# Review uncommitted changes
/codex:review

# Review your branch compared to main
/codex:review --base main

# Run in background (recommended for multi-file changes)
/codex:review --background

This is read-only — Codex won't modify your code. It's perfect for getting a sanity check before pushing or creating a pull request.

/codex:adversarial-review — Challenge Your Assumptions

This is where things get interesting. Instead of just checking for bugs, adversarial review questions your implementation choices:

# Challenge the overall approach
/codex:adversarial-review

# Focus on specific risk areas
/codex:adversarial-review --base main challenge whether this caching strategy is safe

# Run in background with custom focus
/codex:adversarial-review --background look for race conditions and question the retry logic

Use this when you want to pressure-test architectural decisions, not just syntax.

/codex:rescue — Delegate Complex Tasks

When you're stuck on a tricky bug or want Codex to take a crack at a fix:

# Investigate a problem
/codex:rescue investigate why the integration tests are flaky

# Try a fix
/codex:rescue fix the memory leak in the connection pool

# Use a specific model
/codex:rescue --model gpt-5.4-mini --effort medium investigate the CI timeout issue

# Run in background
/codex:rescue --background debug the race condition in the event handler

The rescue command creates a persistent Codex thread that you can resume later or continue directly in Codex.

Managing Background Tasks

When you run commands in the background, use these to track progress:

# Check status of running jobs
/codex:status

# Get results when complete
/codex:result

# Cancel a running task
/codex:cancel

Installation and Setup

Getting started takes less than two minutes:

# Add the marketplace
/plugin marketplace add openai/codex-plugin-cc

# Install the plugin
/plugin install codex@openai-codex

# Reload plugins
/reload-plugins

# Verify installation
/codex:setup

If Codex isn't installed, the setup command can install it for you:

npm install -g @openai/codex

Then authenticate:

!codex login

You can use your existing ChatGPT subscription (including Free tier) or an OpenAI API key.

Configuration Options

The plugin respects your Codex configuration. To customize defaults, create or edit .codex/config.toml in your project root:

model = "gpt-5.4-mini"
model_reasoning_effort = "high"

Or set user-level defaults in ~/.codex/config.toml.

Real-World Example: Reviewing a Feature Branch

Here's a typical workflow when you're about to submit a PR:

# 1. Make sure your changes are committed
git add .
git commit -m "feat: add retry logic to API client"

# 2. Get a standard review
/codex:review --base main

# 3. Challenge the design decisions
/codex:adversarial-review --base main question whether exponential backoff is the right strategy here

# 4. If Codex finds issues, fix them and re-review
/codex:review --base main

# 5. Confident? Push and create your PR
git push origin feature-branch

The adversarial review might surface concerns like: "Is exponential backoff appropriate for this API? What about circuit breakers? Have you considered the thundering herd problem?"

Key Benefits

• No context-switching — Stay in Claude Code while getting Codex's perspective
• Complementary strengths — Claude excels at reasoning, Codex at code-specific patterns
• Background execution — Long-running reviews don't block your workflow
• Session continuity — Transfer conversations between tools without losing context
• Cost-effective — Use your existing ChatGPT subscription or API key
• Read-safe — Reviews are non-destructive; Codex won't modify your code without explicit delegation

Advanced: The Review Gate

For extra safety, you can enable an automatic review gate that runs Codex review before Claude Code completes responses:

/codex:setup --enable-review-gate

Warning: This can create long-running loops and consume significant usage limits. Only enable when actively monitoring.

FAQ