Chrome Dev MCP

chrome-dev-mcp

●An MCP server that attaches to an already-running Chrome tab for real runtime debugging: breakpoints, stepping, and scope variables — plus JS/CSS inspection, console logs, and network capture. Built for web frontend development.

●It talks plain CDP through chrome-remote-interface — no DevTools SDK, no bundled browser — so it debugs the tab you already have open, in your own Chrome, instead of launching an isolated instance.

Demo video

Debugging js

Inspecting html and css

Why This Exists

●Currently, chrome-devtools-mcp is still focused more on browser automation and inspection than full runtime debugging, though it is clearly moving toward exposing more DevTools capabilities, as described in this Let your Coding Agent debug your browser session with Chrome DevTools MCP.

●Meanwhile, the underlying debugging capabilities are already available through tools such as chrome-remote-interface and @jridgewell/trace-mapping.

●This project exists as a faster, independent implementation focused specifically on making Chrome runtime debugging usable for AI agents before similar functionality is officially available in chrome-devtools-mcp.

Architectural difference from chrome-devtools-mcp

●chrome-devtools-mcp runs DevTools SDK models (TargetManager, DebuggerModel, NetworkManager, etc.) directly in Node.js via chrome-devtools-frontend's /mcp/mcp.js entrypoint, backed by a Puppeteer CDP connection — capabilities that go beyond what the raw Chrome DevTools Protocol exposes directly.

●That approach comes with trade-offs: chrome-devtools-frontend is a very large package (it mirrors the entire Chrome DevTools frontend codebase), and the approach relies on the internal structure of the DevTools page remaining stable across Chrome versions.

●This project takes the opposite approach: plain CDP via chrome-remote-interface, no DevTools SDK, minimal dependencies. The result is a lightweight server that is easy to install, audit, and extend.

Limitations

■ Does not track Chrome's active tab automatically. CDP does not expose a tab-switch event, so switching tabs in Chrome does not change the MCP connection — use switch_tab to explicitly reconnect to the tab you want.

■ Iframes, workers, and service workers are not supported at present.

■ WebSocket frames are not captured.

■ Not designed to run alongside chrome-devtools-mcp. Both register overlapping tool names and maintain independent debugger state against the same Chrome target, which causes confusion for the AI and potential state conflicts.

Prerequisites

• Node.js 22+
• Google Chrome

Usage

Chrome

▲Launch Chrome with remote debugging enabled.

chrome.exe --remote-debugging-port=9222 --user-data-dir=C:\chrome-debug-profile
# --user-data-dir can be any empty directory; it keeps the debug session isolated from your normal Chrome profile.

▲Verify remote debugging is active by opening http://localhost:9222/json in a browser — it should return a JSON list of debuggable targets.

▲Open the page you want to debug. The MCP server connects to the active tab at startup. To switch to a different tab later, ask the AI to switch — it will use list_tabs and switch_tab as needed.

Claude Code configuration

Through npm package

With a fixed version

▲Install npm package globally.

npm install -g chrome-dev-mcp

▲Add the server to Claude Code's MCP.

claude mcp add --transport stdio chrome-dev -- chrome-dev-mcp

▲Claude Code's config(~/.claude.json) will look like this:

"mcpServers": {
  "chrome-dev": {
    "type": "stdio",
    "command": "chrome-dev-mcp",
    "args": [],
    "env": {}
  }
},

Always use the latest version

▲Add the server to Claude Code's MCP.

claude mcp add --transport stdio chrome-dev -- npx -y chrome-dev-mcp@latest
# '-y' is not supportted at 20260522. We may change the config below directory.

▲Claude Code's config(~/.claude.json) will look like this:

"mcpServers": {
  "chrome-dev": {
    "type": "stdio",
    "command": "npx",
    "args": [
      "-y",
      "chrome-dev-mcp@latest"
    ],
    "env": {}
  }
},

Through local project

▲Clone this project to local.

▲Add the server to Claude Code's MCP.

claude mcp add --transport stdio chrome-dev -- node "path/to/chrome-dev-mcp/dist/index.js"

▲Claude Code's config(~/.claude.json) will look like this:

"mcpServers": {
  "chrome-dev": {
    "type": "stdio",
    "command": "node",
    "args": ["path/to/chrome-dev-mcp/dist/index.js"],
    "env": {}
  }
}

Validation

●run claude mcp list, and it will print chrome-dev: xxxxx - ✓ Connected.

MCP Tools

☆25 tools in seven groups — six domains plus one cross-cutting tool:

☆All 25 serve one workflow. Two things come first, in either order: the agent learns what goes wrong, and the page reaches the state where it does — by hand, or through the agent's own navigate_tab, reload_tab and breakpoints. From there the agent reads whatever explains it — a console error, a network response, the DOM and its computed CSS, or a paused call stack and its scopes. Once a fix is in, the same tools confirm it: reload_tab, then read again.

☆Several pairs below look mergeable and are deliberately not — docs/tool-boundaries.md records which, and why.

Tab management

Page inspection

Navigation

▲Both work while paused at a breakpoint: the pause ends with the old page, and breakpoints hit again in the new one — so "set a breakpoint, then reload_tab" stops in the page's startup code and returns the call stack where it paused.

▲A failed navigation is reported as an error, not as loaded — Chrome still loads its own error page in that case and fires its load event — and a page whose load event does not fire within 30s comes back as still-loading.

Console

Debugger

Network

▲Unlike get_console_logs, network capture is not retroactive: Network.enable() has no history replay, so capture begins when this server connects to the tab and nothing before that is visible. Requests belonging to a previous page are then pruned on navigation, mirroring the DevTools Network panel default — the new document's own request is kept.

Capture buffers

▲Affects this server only — nothing is cleared in Chrome or in the DevTools UI, and capture keeps running. Clearing cannot be undone: console entries are gone for good, since Console.enable() replays history only at attach time, while cleared network requestIds still resolve in get_network_response_body for as long as Chrome itself holds the body.

Typical debugging workflow

◆Bring Chrome to the desired state manually — navigate to a specific route, trigger a flow, or pause at a breakpoint.

◆Ask the AI what you want to investigate, and it will call get_debugger_state, get_scope_variables, etc. automatically when needed.

◆To share a specific DOM element with the AI during debugging, select it in the Elements panel, then run this in the DevTools console:

window.$0 = $0;

The AI can then call get_inspected_element to read its tag, attributes, and HTML.

# Example sequence Claude might use
get_debugger_state          → { paused: true, callStack: [{ functionName: "handleClick", url: "...", lineNumber: 42 }] }
get_scope_variables         → [{ name: "event", type: "object", value: "MouseEvent" }, ...]
evaluate_at_frame           → expression: "dropTargets.map(t => t.id)"  →  ["list-1", "list-2"]

evaluate_at_frame runs in the paused frame's scope and can read local variables, whereas evaluate_js runs in the global scope and cannot. They stay separate tools so that the pause state — which the caller cannot see — is carried by the tool name instead of an optional parameter: evaluate_js never silently answers from the wrong scope, and evaluate_at_frame never silently answers from the global one.

Development

●Install dependencies by pnpm install, and then:

pnpm dev          # development (tsx watch)
pnpm build        # tsc type-check + compile to dist/
pnpm start        # run compiled build
pnpm test         # run vitest