Codex Control Chrome MCP

Expose the Codex Chrome Extension flow to other Agent tools through MCP.

This project lets MCP clients control the user's normal Chrome profile through the installed Codex Chrome Extension. It is useful when an Agent needs existing tabs, cookies, logged-in sessions, installed extensions, screenshots, console/network events, or raw Chrome DevTools Protocol commands.

This is an independent community project. It is not affiliated with OpenAI, Codex, Google, or Chrome.

• NPM: codex-control-chrome-mcp
• GitHub: iola1999/codex-control-chrome-mcp
• Chrome Extension: Codex Chrome Extension
• Skill: skills/codex-control-chrome-mcp/SKILL.md

Platform Support

| Platform | Status | Notes | | --- | --- | --- | | macOS | Tested | Primary supported platform. | | Linux | Experimental | Manifest path targets Google Chrome under ~/.config/google-chrome. | | Windows | Unsupported | Native Messaging registration uses registry keys on Windows and is not implemented yet. |

Node.js 20 or newer is required. npm Trusted Publishing for releases uses Node.js 24 in GitHub Actions.

Browser Support

Both Chromium browsers use the same Codex extension and the same chrome-extension:// origin, so a single manifest works for either.

| Browser | Status | Notes | | --- | --- | --- | | Google Chrome | Tested | Default target. | | Microsoft Edge | Supported | Same extension and native-messaging mechanism; installs to the Edge NativeMessagingHosts directory. |

Commands accept --browser <chrome\|edge\|all>. Without the flag, install-native-host installs for every supported browser whose profile directory exists, uninstall-native-host targets every browser it previously installed for, and status reports both.

Quick Start

Install and enable the Codex Chrome Extension in the Chrome or Edge profile you want to automate.

Install the package globally, then register the native host (auto-detects the browsers present):

npm install -g codex-control-chrome-mcp
codex-control-chrome-mcp install-native-host

A global install gives the native host a stable path, so its launcher execs Node directly against the installed CLI with no per-connection npx cost. To target one browser explicitly:

codex-control-chrome-mcp install-native-host --browser edge

Configure your Agent to use the MCP stdio server through the installed binary:

{
  "type": "stdio",
  "command": "codex-control-chrome-mcp",
  "args": ["--stdio"],
  "startup_timeout_sec": 30
}

If your MCP client does not inherit a shell PATH that includes npm's global bin directory (common for GUI apps), use the absolute path from npm prefix -g — for example /opt/homebrew/bin/codex-control-chrome-mcp — as command.

Check status and uninstall:

codex-control-chrome-mcp status
codex-control-chrome-mcp uninstall-native-host   # restores the previous Codex native host manifest

Without a global install

npx -y codex-control-chrome-mcp@latest <command> still works for every command. Be aware that npx … install-native-host writes a launcher that re-runs npx on every extension connection; a cold or evicted npx cache can add seconds and may exceed the extension's connect timeout (the bridge then looks stuck "not connecting"). The installer detects the npx temp copy and keeps that launcher as a fallback — install globally and re-run install-native-host for the fast, stable path.

Agent Skill

If your Agent supports skills, install or reference the bundled skill folder:

skills/codex-control-chrome-mcp

The skill documents the recommended MCP tool order for:

• status checks
• tab listing and claiming
• CDP attach and command execution
• screenshots
• network and console event reads
• tab finalization

Security Notes

This project controls the user's normal Chrome profile. MCP clients connected to it can inspect page contents and send raw CDP commands to claimed tabs.

Only install and run it on machines and Chrome profiles you own or are explicitly authorized to automate. Do not send browser cookies, password stores, profile databases, tokens, or private session files in issues or logs.

See SECURITY.md for the security model and reporting process.

How It Works

The Codex Chrome Extension does not need an external Chrome remote debugging port. It uses Chrome Native Messaging and the extension's chrome.debugger permission:

Chrome extension
  -> chrome.runtime.connectNative("com.openai.codexextension")
  -> codex-control-chrome-mcp native host
  -> local MCP bridge socket
  -> chrome.debugger.attach / chrome.debugger.sendCommand
  -> CDP

Because the control entrypoint is inside the normal Chrome profile, existing cookies, logged-in sessions, tabs, and extensions can be reused.

Read more:

• Architecture
• Troubleshooting & Debugging Playbook
• Install And Uninstall
• Official Socket Probe Notes
• Release Process

Development

Install dependencies:

npm ci

Run checks:

npm run ci

Run the MCP server locally:

node ./bin/codex-control-chrome-mcp.js --stdio

Run native host mode locally for development:

node ./bin/codex-control-chrome-mcp.js --native-host

Troubleshooting

A Codex update stopped the bridge

Codex App/extension updates re-register their own com.openai.codexextension native-messaging manifest, which overwrites this project's proxy registration (the bundled host binary has even been renamed across releases). The symptom is status showing sockets: [], registered: false, and a manifest path back inside the Codex bundle.

The MCP stdio server now self-heals: on startup it re-asserts the manifest when it detects it was reverted, so you usually do not need to re-run install-native-host. Because Chrome only reads the manifest when the extension reconnects, reload the Codex Chrome Extension (or restart Chrome) once after a Codex update to bring the bridge back. Set CODEX_CONTROL_CHROME_NO_AUTO_REGISTER=1 to disable the auto re-register.

If Codex App integration stops working, uninstall this native host to restore the backed-up manifest:

npx -y codex-control-chrome-mcp@latest uninstall-native-host

If tab or CDP tools fail, use the bundled skill workflow: list tabs again, claim only current tab IDs, attach before raw CDP calls, and read CDP events after enabling the relevant domain.

"Debugger is not attached" / flaky CDP under concurrency

CDP tools self-heal a stale debugger attachment since 1.4.0 (attach is verified, and a lost attachment is recovered with detach → re-attach → retry). If you still see attach flakiness — most likely when several browser-control stacks share one Chrome and contend for the single debugger per tab — see the Troubleshooting & Debugging Playbook for the root cause, reference points (official client, extension service worker), and the scripts/concurrency-check.mjs soak test.

See Install And Uninstall for the full per-browser checklist (the registered flag and host classification).

License

MIT