DevTools MCP servers

Browser vendors ship their own MCP servers that give a model the browser’s developer tools: performance traces, network and console inspection, the accessibility tree. They attach to a browser that is already running, through its DevTools endpoint. sbrs devtools starts such a browser for them, and the sbrs-mcp Pure CDP server can hand out the endpoint of the browser it drives, so a vendor server and this crate’s tools can work on the same tabs.

Several servers, one browser.

sbrs devtools#

sbrs devtools

It launches Chrome with the Pure CDP engine (no chromedriver), with its DevTools endpoint on 127.0.0.1:9222 and a throwaway profile, and prints:

• the DevTools HTTP endpoint (http://127.0.0.1:9222) and the browser WebSocket URL (ws://127.0.0.1:9222/devtools/browser/<id>),
• a ready-to-paste client config for chrome-devtools-mcp and one for Playwright MCP,
• the claude mcp add commands for Claude Code.

The browser keeps running until you press Ctrl+C (or send SIGTERM), which closes it and exits with status 0. Closing the browser window ends the command too.

The global options that make sense for a Pure CDP browser apply as well, written before devtools: --browser chrome|chromium|edge|brave|..., --headed, --user-agent, --locale, --ad-block, --extension-dir and --proxy-list. --uc and --cdp change nothing here: this engine never uses chromedriver.

The --json line is the first line on standard output, so a script can read it and start its client.

The endpoint of an sbrs-mcp session#

The Pure CDP server (sbrs-mcp --server cdp) has a tool for this: get_devtools_endpoint returns the same addresses and configs for the browser that start_browser launched, or running: false before one runs. See MCP servers.

From Rust, Browser::devtools_endpoint() returns a DevToolsEndpoint with http_url(), websocket_url(), chrome_devtools_mcp_config(), playwright_mcp_config() and claude_code_commands(), and LaunchOptionsBuilder::debugging_port(9222) fixes the port:

use seleniumbase_rs::sb_cdp::{Browser, LaunchOptions};# async fn demo() -> Result<(), seleniumbase_rs::SeleniumBaseError> {let options = LaunchOptions::builder().debugging_port(9222).build()?;let browser = Browser::launch(options).await?;let endpoint = browser.devtools_endpoint();println!("{}", endpoint.chrome_devtools_mcp_config());# Ok(())# }

Google chrome-devtools-mcp#

The npm package chrome-devtools-mcp (by the Chrome DevTools team, source at https://github.com/ChromeDevTools/chrome-devtools-mcp) runs on Node.js (^20.19.0, ^22.12.0 or 23 and later) and drives Chrome through Puppeteer. With sbrs devtools running, the client config is:

{  "mcpServers": {    "chrome-devtools": {      "command": "npx",      "args": [        "-y",        "chrome-devtools-mcp@1.11.0",        "--browserUrl=http://127.0.0.1:9222",        "--no-usage-statistics",        "--no-performance-crux"      ]    }  }}

claude mcp add chrome-devtools -- npx -y chrome-devtools-mcp@1.11.0 --browserUrl=http://127.0.0.1:9222 --no-usage-statistics --no-performance-crux

• --browserUrl (aliases --browser-url, -u) attaches to a running Chrome. --wsEndpoint ws://127.0.0.1:9222/devtools/browser/<id> (alias -w) is the other way in, with the WebSocket URL sbrs devtools prints; --wsHeaders adds headers to it.
• --no-usage-statistics turns off the usage statistics the server sends to Google by default (setting CI or CHROME_DEVTOOLS_MCP_NO_USAGE_STATISTICS does too). --no-performance-crux stops its performance tools from looking up page URLs in Google’s CrUX data.
• Without an attach option the server launches a Chrome of its own (--headless, --isolated, --channel, --executablePath, --userDataDir).
• --autoConnect (Chrome 144 and later) attaches to the Chrome you use every day, after you enable chrome://inspect/#remote-debugging in it. On macOS 27 it fails with Could not find DevToolsActivePort, because the system denies the terminal app access to Chrome’s profile folder (open issue #3089). The workaround is System Settings > Privacy & Security > Files & Folders, the terminal app, Google Chrome. --browserUrl avoids the problem.

Microsoft Playwright MCP#

The npm package @playwright/mcp (source at https://github.com/microsoft/playwright-mcp) needs Node.js 18 or later. It attaches over the DevTools Protocol with --cdp-endpoint, which takes the HTTP address or the WebSocket URL:

{  "mcpServers": {    "playwright": {      "command": "npx",      "args": ["-y", "@playwright/mcp@0.0.83", "--cdp-endpoint=http://127.0.0.1:9222"]    }  }}

claude mcp add playwright -- npx -y @playwright/mcp@0.0.83 --cdp-endpoint=http://127.0.0.1:9222

• Playwright’s own documentation says a DevTools Protocol connection (connectOverCDP) works with Chromium browsers only and is “significantly lower fidelity” than its own protocol. --cdp-header adds headers and --cdp-timeout (default 30000 ms) bounds the connection.
• --extension attaches to the Chrome or Edge you use every day through the Playwright extension instead of a debugging port.
• Without an attach option it launches its own browser: --browser chrome|firefox|webkit|msedge, --headless, --isolated, --user-data-dir. Its Firefox and WebKit are Playwright’s patched builds, not the browsers you install.

Microsoft Edge#

Edge is Chromium, so the same endpoint and configs work:

sbrs --browser edge devtools# or, for an Edge somewhere else:sbrs devtools --browser-path "/Applications/Microsoft Edge.app/Contents/MacOS/Microsoft Edge"

Playwright MCP supports Edge (--cdp-endpoint, --extension, or --browser msedge). chrome-devtools-mcp supports only Google Chrome and Chrome for Testing officially and says other Chromium browsers may work; one reported difference is that Edge tabs opened with Ctrl+T were missing from list_pages (issue #2880).

Firefox: Mozilla’s firefox-devtools-mcp#

Firefox does not speak the Chrome DevTools Protocol, so neither server above can attach to it, and sbrs devtools refuses --browser firefox. Mozilla’s @mozilla/firefox-devtools-mcp (source at https://github.com/mozilla/firefox-devtools-mcp, Node.js 20.19 or later, Firefox 100 or later) drives Firefox through WebDriver Classic and WebDriver BiDi:

{  "mcpServers": {    "firefox-devtools": {      "command": "npx",      "args": ["-y", "@mozilla/firefox-devtools-mcp@latest", "--headless", "--viewport", "1280x720"]    }  }}

To attach to a Firefox that is already running, start it with both --marionette and --remote-debugging-port, and run the server with --connect-existing --marionette-port 2828.

Safari: safaridriver —mcp#

Safari 27 ships an MCP server inside safaridriver, which is part of macOS:

{  "mcpServers": {    "safari-mcp": {      "command": "/usr/bin/safaridriver",      "args": ["--mcp"]    }  }}

claude mcp add safari-mcp -- /usr/bin/safaridriver --mcp

It needs two Safari settings: Advanced, “Show features for web developers”, and then Developer, “Allow remote automation and external agents” (see https://webkit.org/blog/18136/introducing-the-safari-mcp-server-for-web-developers/).

Security#

What was checked#