cast-mcp

MCP server for Google Cast — discover devices, play media, control volume, launch apps, and manage queues over stdio.

Installation

npx -y @daanrongen/cast-mcp

Tools (17 total)

Domain	Tools	Coverage
Discovery	discover_devices	Scan local network for Cast-enabled devices via mDNS
Media	play_media, pause, resume, stop, seek, get_media_status	Playback control and media status
Queue	load_queue, queue_next, queue_prev	Playlist queuing and navigation
Apps	get_status, launch_app, stop_app	Application lifecycle on Cast receivers
Volume	get_volume, set_volume, mute, unmute	Volume and mute control

Setup

No environment variables are required. The server discovers Cast devices automatically via mDNS on the local network.

Claude Desktop

Edit ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "cast": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@daanrongen/cast-mcp"]
    }
  }
}

Or via the CLI:

claude mcp add cast -- npx -y @daanrongen/cast-mcp

Development

bun install
bun run dev        # run with --watch
bun test           # run test suite
bun run build      # bundle to dist/main.js
bun run inspect    # open MCP Inspector in browser

Inspecting locally

bun run inspect launches the MCP Inspector against the local build:

bun run build && bun run inspect

This opens the Inspector UI in your browser where you can call any tool interactively and inspect request/response shapes.

Architecture

src/
├── config.ts               # (no env config required)
├── main.ts                 # Entry point — ManagedRuntime + StdioServerTransport
├── domain/
│   ├── CastClient.ts       # Context.Tag service interface
│   ├── errors.ts           # CastError, DeviceNotFoundError
│   └── models.ts           # Schema.Class models (CastDevice, MediaStatus, …)
├── infra/
│   ├── CastClientLive.ts   # Layer.scoped — mDNS discovery + castv2 connections
│   └── CastClientTest.ts   # In-memory test adapter
└── mcp/
    ├── server.ts           # McpServer wired to ManagedRuntime
    ├── utils.ts            # formatSuccess, formatError
    └── tools/              # discovery.ts, media.ts, queue.ts, apps.ts, volume.ts