vencord-mcp

An MCP server that lets a coding agent read a running Discord client the way a plugin author reads it: stores, webpack modules, patches, React props, and the gateway traffic itself.

It talks to any Chromium started with --remote-debugging-port, so it works on Discord with Vencord or Equicord injected, and most of it works on any Electron app with a minified webpack bundle.

Why this exists

Two halves of this already existed separately, and neither was useful on its own.

There are several generic Electron and Chrome DevTools MCP servers. They take screenshots, read the console, and evaluate JavaScript, but they know nothing about webpack, Flux stores, or Vencord patches, so an agent using them spends its budget rediscovering the same boilerplate every session.

On the other side, Vencord Companion knows exactly the right things: whether a webpack find is unique, whether a patch's match compiles. But it is a VSCode extension, built for a human reading it in an editor.

Nothing connected the two. This does.

Related MCP server: instagit

What it changes

The normal loop for writing a plugin is: open devtools, hunt through a minified bundle, write a regex and hope, compile, restart Discord, find out. Each mistake costs a restart.

With these tools the loop closes in seconds, and more importantly the agent stops guessing. test_patch answers "would this patch actually run" before anything is built. capture_websocket shows what the server really sent instead of what the interface implied. react_props recovers the name of a failure whose UI only shows a number.

Install

npm install

Register it with your MCP client. Most of them take a config block like this:

{
  "mcpServers": {
    "vencord": {
      "command": "node",
      "args": ["/absolute/path/to/vencord-mcp/src/index.js"]
    }
  }
}

Clients that ship a CLI usually have a one-liner for the same thing, along the lines of mcp add vencord -- node /absolute/path/to/vencord-mcp/src/index.js.

Then start Discord with the debugger open:

Discord.exe --remote-debugging-port=9223

The port only listens on localhost, but it is a debugger: anything that can reach it can read your session. Close and reopen Discord normally when you are done.

Tools

Read-only unless marked otherwise.

Every tool takes port (default 9223) and an optional urlHint for when more than one page target is open.

The three that are worth the install

test_patch runs the same check Vencord runs at startup, against the build that is actually running. A find that matches no module means the patch silently never runs, and a find that matches several means Vencord patches all of them. Both are invisible until the plugin misbehaves in a way that looks like something else.

test_patch(find: '"2026-08-video-guard"', match: 'variations:\\{.{0,120}?\\}\\}', replace: 'variations:{}')
-> "find is unique and match hits exactly once"

patch_status answers the question test_patch cannot: did it actually run. Vencord drops a patch from its pending list once its module loads, so anything still listed never matched. That is the failure that costs the most time, because the plugin loads, reports no error, and quietly does nothing. Patches declared all stay listed forever by design and are reported separately so they do not read as broken.

capture_websocket decodes Discord's voice opcodes by name: IDENTIFY, READY, SESSION_DESCRIPTION, VIDEO, MEDIA_SINK_WANTS. Reading them is the difference between "the video did not appear" and "the server offered ssrc 267, the client asked for it at full quality, and no packets followed", which are different bugs with different fixes.

One caveat: the Network domain only records sockets it saw being created. A connection that was already open when the capture started is reported as (socket opened before capture) — the frames are still decoded, because their content identifies the protocol, but the URL is unknown. Make the client reconnect during the window to get it.

Notes

Discord ships a strict CSP that blocks eval. Every evaluation here sets allowUnsafeEvalBlockedByCSP, which is the documented way for a debugger to run anyway; without it every call fails with an unhelpful EvalError.

Each tool call opens its own debugger session and hangs up. Holding one open between calls would only create state to get out of sync.

Tests

node test/smoke.js

It speaks the real protocol to the real server over stdio: initialize, list the tools, then exercise the live path against a Discord on port 9223 if one is running. A server that starts is not the same as a server that answers.

License

GPL-3.0-or-later, matching Vencord.