Codex CLI MCP Server

An MCP server that allows Claude Code to interact with the OpenAI Codex CLI. If you have a ChatGPT subscription and a claude code subscription, you can use this tool to get the benefits of both, as a $20 ChatGPT subscription gives you access to GPT-5 for free in Codex CLI.

Features

• Complete Codex Integration: Access all Codex CLI capabilities through MCP
• GPT-5 Model: Powered by OpenAI's most capable model
• Sandbox Safety: Configurable execution modes (read-only, workspace-write, full-access)
• Progress Tracking: Real-time updates for long-running operations
• Git Integration: Apply Codex-generated diffs directly to repositories
• Flexible Configuration: Environment variables and config file support

Installation

1. Install Codex CLI (required):

   npm install -g @openai/codex

2. Add to Claude Code using npx:

   claude mcp add codex-cli-mcp-tool -- npx -y codex-cli-mcp-tool

   Or install globally first:

   npm install -g codex-cli-mcp-tool

3. Configure Authentication:

   # Option 1: Use API key
   export OPENAI_API_KEY=your-api-key
   
   # Option 2: Login with ChatGPT account
   codex login

Available Tools

ask-codex

Execute Codex with comprehensive parameter support for code analysis, generation, and assistance.

Parameters:

• prompt (required): Your query or instruction
• model (optional): gpt-5 (default and only supported model)
• sandbox (optional): read-only, workspace-write, danger-full-access
• approval (optional): untrusted, on-failure, on-request, never
• image (optional): Image file path(s) to include
• config (optional): Configuration overrides
• timeout (optional): Maximum execution time

Example:

ask-codex "Explain this code: @main.py" sandbox="read-only"

exec-codex

Non-interactive Codex execution for automation workflows.

Parameters:

• prompt (required): Command or instruction
• model (optional): Always gpt-5
• sandbox (optional): Sandbox mode
• timeout (optional): Execution timeout

apply-diff

Apply the latest Codex-generated diff to your git repository.

Parameters:

• dryRun (optional): Preview changes without applying
• validate (optional): Validate before applying

Utility Tools

• ping: Test MCP connection
• help: Show detailed help information
• version: Display version information

Configuration

Environment Variables

OPENAI_API_KEY=sk-...           # OpenAI API key
CODEX_MODEL=gpt-5               # Default model
CODEX_SANDBOX_MODE=read-only    # Default sandbox mode

Config File (~/.codex/config.toml)

[model]
provider = "openai"
default = "gpt-5"
reasoning_effort = "medium"

[sandbox]
default_mode = "read-only"
permissions = ["disk-read-access"]

[approval]
policy = "untrusted"
trusted_commands = ["ls", "cat", "grep"]

Sandbox Modes

• read-only: Safe exploration, no file modifications
• workspace-write: Limited modifications within project
• danger-full-access: Full system access (requires confirmation)

Examples

Code Analysis

ask-codex "Review this function for security issues: @auth.py"

Code Generation

ask-codex "Generate unit tests for the User class" sandbox="workspace-write"

Debugging

ask-codex "Fix the bug in login function" approval="on-request"

File Operations

ask-codex "Create a new React component for user profile" sandbox="workspace-write"

Apply Changes

ask-codex "Refactor this code to use async/await"
apply-diff validate=true

Troubleshooting

Common Issues

1. Codex CLI not found:

   npm install -g @openai/codex

2. Authentication failed:

   # Set API key
   export OPENAI_API_KEY=your-key
      
   # Or login
   codex login

3. Permission denied:

   • Use appropriate sandbox mode
   • Check approval policy settings
   • Verify file permissions

4. Rate limits:

   • Wait before retrying
   • Check OpenAI account quota

Debug Mode

Enable debug logging:

DEBUG=true codex-cli-mcp-tool

Development

Setup

git clone <repository>
cd codex-cli-tool
npm install
npm run build
npm run dev

Testing

npm test
npm run lint

Acknowledgments

This project is based on the excellent Gemini MCP Tool by jamubc. We adapted their architecture and patterns to create this Codex CLI integration.

License

MIT License - see LICENSE file for details.

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests
5. Submit a pull request

Support

• GitHub Issues: Report bugs and feature requests
• OpenAI Codex: https://github.com/openai/codex