dia mcp

Dia Browser MCP server. Let an AI agent use the Dia browser you already have open: your tabs, your logins, your session. No debug port, no restart, no second browser.

dia-mcp is the Dia equivalent of chrome-devtools-mcp. It exposes the Chrome DevTools Protocol of a live Dia tab over MCP, so any agent client (Claude Desktop, Cursor, Hermes, VS Code) can read pages, click, type, inspect network traffic and console errors, and take screenshots. Built with FastMCP.

Also searched for as: Dia MCP, Dia Browser MCP, Dia MCP DevTools, Dia MCP server, Dia DevTools MCP.

your agent  →  mcp_server.py  →  bridge.py (127.0.0.1:9777)  →  Dia extension  →  chrome.debugger  →  your tab

The browser is never launched or restarted. Dia stays exactly as it is.

Requirements

Related MCP server: Chrome DevTools MCP

Setup

Three steps, about two minutes.

0. Install FastMCP

python3 -m pip install fastmcp

The bridge itself has no dependencies; only the MCP server needs FastMCP.

1. Start the bridge

python3 tools/bridge.py serve

Leave it running. This is the local channel between the extension and your agent. If you skip it, the MCP server starts it for you on first use.

2. Add the extension to Dia

1. Open Dia and go to chrome://extensions

2. Turn on Developer mode in the top right corner

3. Click Load unpacked

4. Choose the extension folder inside this repo

One time step. Dia keeps it after a restart.

3. Connect your agent

Hermes:

hermes mcp add dia-mcp \
  --command "$(which python3)" \
  --args "$(pwd)/mcp_server.py"

Then run /reload-mcp in a session, or start a new one.

Any other MCP client, add this and replace the path:

{
  "mcpServers": {
    "dia-mcp": {
      "command": "python3",
      "args": ["/absolute/path/to/mcp_server.py"]
    }
  }
}

Check that it works

Ask your agent: "call list_pages and tell me the page ids". You should see the tabs that are open right now.

Or test the bridge directly:

python3 tools/selftest.py

It prints one line per check and ends with 18/18 checks passed.

Tools

The names and arguments are the same as chrome-devtools-mcp, so instructions and prompts written for that server work here unchanged. Pages are addressed by pageId and elements by uid from take_snapshot, exactly as there.

Pages

Inspection

Interaction

Network and console

Emulation and capture

Present for parity, unavailable on Dia (each fails with a clear message)

Extras beyond chrome-devtools-mcp

dia mcp vs Chrome DevTools MCP

chrome-devtools-mcp is the official Chrome server. It is excellent, and on most tasks it is the right tool. The difference is where it gets its browser.

What dia mcp does the same

Same tool names, same arguments, same pageId and uid semantics. The differences are under the hood:

What dia mcp does not do

Every unavailable tool still exists in the list and fails with an explicit reason, so an agent that expects the full surface gets a clear answer instead of a missing tool.

What about chrome-devtools-mcp pointed at Dia?

It mostly works. Launch Dia once with --remote-debugging-port=9222, then run that server with --browserUrl http://127.0.0.1:9222. In testing on Dia 1.56, 28 of its 32 tools worked. resize_page and take_heapsnapshot failed, and background tabs behave oddly until they are focused. The catch is the flag: Dia ignores it when the browser is already running, so your session has to be closed and reopened. If you are fine with that, that route gives you more tools. If you want to attach to the browser you are in, use this repo.

FAQ

Is this a fork of chrome-devtools-mcp? No. It is a small MCP server built with FastMCP, a local bridge, and a browser extension. It uses the same underlying protocol, chrome.debugger.

Does it need --remote-debugging-port? No. That flag only works at launch. Dia accepts the request through an extension instead, so no restart is needed.

Can it see sites I am logged into? Yes, that is the point, and the trade-off. The agent only reaches the tab you attach to, and only while the bridge is running. Call dia_detach, or stop the bridge, when you are done.

Does it work with Claude Desktop, Cursor, or Hermes? Yes. It is a plain stdio MCP server, so any client that speaks MCP can run it.

Windows or Linux? No. Dia is macOS only.

Why does a call time out on a tab I am not looking at? Dia freezes background tabs, so timers and requests stall there. Every page tool focuses the tab first. If you still see a timeout, the extension is not loaded, or the repo moved after it was loaded.

What is in this repo

License

MIT. Use it, change it, ship it, sell it. Keep the copyright notice with the code.