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To connect Google Chrome’s DevTools MCP server to Codex CLI, run codex mcp add chrome-devtools -- npx chrome-devtools-mcp@latest in a shell where Codex CLI and Node’s npx are available. Then ask Codex to check the performance of https://developers.chrome.com; the documented smoke test opens a browser window and records a performance trace. The server lets Codex interact with Chrome through browser and DevTools tools.
What the Chrome DevTools MCP server does in Codex
The Chrome DevTools MCP server connects Codex to Chrome so an agent can use browser interaction, live inspection, and debugging capabilities. It is part of Chrome DevTools for agents, which also includes a CLI and agent skills. The MCP server exposes tools for a client such as Codex to discover and invoke using structured input. Chrome’s getting-started guide describes the server and its capabilities.
This setup is for Codex CLI. The documented command registers a server under the name chrome-devtools and launches the chrome-devtools-mcp npm package through npx. You do not need a physical device or accessory.
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- Check prerequisites. Make sure Codex CLI and Node.js’s
npxcommand are available in the environment where you will run Codex. - Register the server. Run this command in your terminal:
codex mcp add chrome-devtools -- npx chrome-devtools-mcp@latest - Start or continue a Codex session. Codex can then discover and use the registered MCP server. If you manage MCP settings by editing a configuration file, Codex CLI and the IDE extension share
~/.codex/config.toml, according to OpenAI’s Codex MCP documentation. - Run the smoke test. Ask Codex: “Check the performance of
https://developers.chrome.com.” Chrome’s guide describes a working result as a browser window opening and a performance trace being recorded. This is the documented check, not a guarantee that every environment will behave identically.
Choose which Chrome session Codex can use
By default, Chrome DevTools for agents starts a new Chrome instance. Use that default when you do not need a pre-existing browser profile or logged-in session. To use an existing Chrome instance instead, Chrome documents two connection modes; the right choice depends on Chrome version and whether you prefer an approval prompt or explicit remote-debugging setup. See the Chrome DevTools for agents configuration guide for the current instructions.
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| Mode | Requirements and setup | Session implications |
|---|---|---|
| New Chrome instance (default) | No existing-session connection flags are needed. | Uses a new browser instance rather than connecting to an already-open session. |
| Automatic connection | Chrome 144 or newer; enable remote debugging at chrome://inspect/#remote-debugging, add --autoConnect to the server arguments, and approve Chrome’s permission prompt when it appears. |
Connects to an existing Chrome session after you grant permission. An authenticated session may expose logged-in accounts, cookies, and other browser data to the agent. |
| Manual connection | Start Chrome with remote debugging enabled and a custom user-data directory; configure the server with --browser-url=http://127.0.0.1:9222, using the same port as the Chrome launch command. |
Connects to the Chrome instance at the specified debugging URL. The dedicated profile helps keep the debugging session separate from your usual browser profile. |
Automatic connection to an existing session
Chrome’s documented automatic flow requires Chrome 144 or newer. Enable remote debugging in chrome://inspect/#remote-debugging, add the --autoConnect argument to the MCP server, and accept Chrome’s connection prompt when the agent attempts to connect. If the prompt does not appear, first confirm the browser version and that remote debugging is enabled.
For a Codex TOML entry, the documented server executable and arguments can be expressed like this:
[mcp_servers.chrome-devtools]
command = "npx"
args = ["-y", "chrome-devtools-mcp@latest", "--autoConnect"]This expresses Chrome’s documented arguments in Codex’s server configuration format. Configuration syntax can change, so check the current Codex MCP configuration documentation if your installed Codex version rejects the entry.
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For manual mode, launch Chrome with remote debugging enabled and a custom user-data directory, then pass the browser URL to the MCP server. The launch commands differ by operating system; use the examples in Chrome’s configuration guide rather than guessing a platform-specific command. The debugging port and the URL passed to --browser-url must match. A Codex configuration entry uses the same executable with the manual connection argument:
[mcp_servers.chrome-devtools]
command = "npx"
args = ["-y", "chrome-devtools-mcp@latest", "--browser-url=http://127.0.0.1:9222"]Use a dedicated profile and close the debugging-enabled Chrome instance when finished. The project’s advanced-usage documentation warns that applications on the same machine can connect to the debugging port and control the browser while it is open; the configuration guide also warns that connecting an existing session exposes its logged-in accounts, cookies, and other data to the agent.
Protect browser sessions and local debugging access
Connecting an agent to an authenticated browser is a security decision, not just a convenience setting. Chrome warns that an agent connected to an active authenticated session may be able to act on your behalf. Treat the browser session’s contents and account state as accessible to the agent. Only connect an agent you trust, and avoid exposing a personal or sensitive profile when a separate profile will do.
- Prefer the default fresh Chrome instance when the task does not require existing cookies or account access.
- For an existing-session workflow, consider a separate Chrome profile with only the accounts and data needed for the task.
- In manual mode, keep the debugging endpoint local, use the documented dedicated profile and port, and close Chrome with remote debugging enabled when the work is done.
- Do not assume a local debugging port is harmless simply because it is bound to your own machine; the project warns that local applications can use it to control the browser while it remains open.
Troubleshoot common setup failures
Codex does not recognize the MCP server
Confirm that the add command completed in the environment where you run Codex, and that the registered server name is chrome-devtools. If you use a manually edited configuration, check the current Codex configuration format and make sure the server entry is in ~/.codex/config.toml. Codex CLI and the IDE extension share that configuration file, but an entry with invalid TOML or outdated syntax will not load.
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The documented registration command depends on Node’s npx. Install or enable a Node.js environment that provides npx, then run the Codex MCP add command again. If npx is available in one terminal but not another, check the shell environment used to launch Codex.
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The agent opens a new browser instead of the one you expected
A new Chrome instance is the default. To attach to an existing one, select automatic connection or manual remote-debugging mode and use the corresponding argument; do not expect the default registration command to reuse a personal session automatically.
Automatic connection does not attach
Verify Chrome is version 144 or newer, remote debugging is enabled at chrome://inspect/#remote-debugging, and the server arguments include --autoConnect. When Chrome asks permission for the agent to connect, approve it. This automatic flow is documented specifically for Chrome 144 and newer.
Manual connection cannot reach Chrome
Check that Chrome was launched with remote debugging enabled, that its user-data directory is the intended dedicated profile, and that the port in the launch command matches the port in --browser-url. For the documented example, both use port 9222 and the URL is http://127.0.0.1:9222. Follow the operating-system-specific launch example in Chrome’s configuration guide if you are unsure how to start Chrome with those settings.
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Use the documented test request for https://developers.chrome.com and confirm that the browser window opens. If it does not, first resolve the server startup or connection issue; if the browser opens but no trace is recorded, make sure Codex is being asked to perform the performance check rather than merely visit the page.
Or skip the browser setup
If your goal is to capture a website screenshot rather than interactively inspect Chrome, ScreenshotNeo is a screenshot API and MCP server for developers. Its one-request API returns a PNG, JPEG, WebP, or PDF. The following cURL example saves a WebP screenshot of https://developers.chrome.com:
curl -G "https://api.screenshotneo.com/v1/shot" -d access_key=YOUR_API_KEY --data-urlencode url=https://developers.chrome.com -o shot.webpSee the ScreenshotNeo API documentation for parameters and setup. Python:
import requests
r = requests.get("https://api.screenshotneo.com/v1/shot", params={"access_key": "YOUR_API_KEY", "url": "https://developers.chrome.com"}, timeout=90)
open("shot.webp", "wb").write(r.content)Node.js:
const q = new URLSearchParams({ access_key: 'YOUR_API_KEY', url: 'https://developers.chrome.com' });
const res = await fetch(`https://api.screenshotneo.com/v1/shot?${q}`);ScreenshotNeo accepts cookie or consent banners as a visitor and removes more than 60 known consent platforms, newsletter popups, and chat widgets before capture; each of those steps can be turned off. Bot checks or CAPTCHAs, blank pages, timeouts, failed loads, and cache hits are not billed, and response headers report the page verdict and billing status. It also provides an MCP server for Claude, Cursor, and other MCP clients, with tools for screenshots, page information, and PDFs. The Free plan includes 1,000 shots per month without a card; paid plans start at $5 for 3,000 shots. Sign up for ScreenshotNeo and get 1,000 free screenshots a month with no card.
Performance, reliability, and cost considerations
The Chrome DevTools MCP setup starts a browser process or connects to a running one, so whether it is suitable depends on whether the task needs a live, inspectable browser session. A performance trace is the documented smoke-test outcome; the setup guide does not establish a general runtime, reliability rate, or cost for all Codex and Chrome environments. For troubleshooting, separate the stages: server registration and startup, browser launch or connection, and the requested browser task.
For a task that only needs a rendered screenshot or PDF rather than interactive DevTools access, a screenshot API may avoid managing a browser process yourself. ScreenshotNeo’s stated billing behavior distinguishes clean captures from failed or cache-hit requests, and its monthly plans are published on its site; check current terms and plan details before choosing based on volume.
Frequently Asked Questions
Does connecting Chrome DevTools MCP require a Chrome extension?
The documented Codex setup registers and runs the MCP server with Codex CLI and npx; the cited setup instructions do not specify an extension as a requirement.
Can Codex use a Chrome profile that is already signed in?
Yes, through Chrome’s documented automatic or manual existing-session connection modes, but doing so exposes that session’s account state and browser data to the agent.
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Is the Chrome 144 requirement for every connection mode?
No. Chrome 144 or newer is specified for the automatic existing-session connection flow; the default new instance and manual connection are separate modes.
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