roomcast-mcp

An MCP server that plays audio on the speakers in your home: Sonos, Google Cast (Chromecast, Nest speakers and displays, Cast groups) and DLNA renderers. Give it audio URLs or one playlist URL, and it plays them in the room you name, one after another, with a queue you can inspect and edit.

Ask Claude "play the latest episode of that podcast in the kitchen", "put on a jazz station in the living room" or "what's in the queue? drop the second one", and it happens on the real speakers, from the Claude app on your phone or from any other MCP client.

MCP client (Claude app, Claude Code, ...)
    │  play_media(room="Kitchen", playlist_url=…)
    ▼
roomcast, on an always-on machine on your LAN
    │ fetches the playlist, follows each redirect chain (public addresses only)
    ├──UPnP (SoCo)────────────▶ Sonos
    ├──Cast v2 (pychromecast)─▶ Chromecast, Nest speakers and displays, Cast groups
    └──UPnP AV (async-upnp)───▶ other DLNA renderers (TVs, AV receivers, ...)

roomcast talks to the speakers directly on the LAN. It needs no speaker cloud account, no developer registration and no credentials of any kind, and it does not look for audio itself: it plays what it is given.

Speakers

list_rooms shows every speaker with its kind, and every speaker also answers to kind:name (cast:Kitchen). Sonos speakers also announce themselves as DLNA renderers; the DLNA side skips them. When two kinds share a name, the plain name goes to the one listed first in ROOMCAST_PLAYERS.

I can only test on the speakers I own (a few Sonos and Nest devices). Other DLNA renderers and Cast devices should work, but are best effort; reports and fixes are welcome.

Related MCP server: Music Assistant MCP

What it plays

• A playlist URL: M3U or M3U8, up to 100 entries and 1MB. Titles come from #EXTINF and the show or artist from #EXTART. An HLS playlist plays as the one stream it is. A URL that turns out to be a single audio file or stream plays as that.

• Items: up to 100 {url, title?, subtitle?}, for audio that is not in a playlist.

Every entry must be a public http(s) URL; see Security. It cannot play Spotify, YouTube or Apple Music: they offer no direct audio URLs.

Things that work well:

• Podcasts: Claude reads a show's RSS feed, or a podcast tool hands it episode URLs.

• Internet radio: station stream URLs, from Radio Browser for example.

• Another MCP server's playlist: a tool that returns one playlist URL for "the news" or "my podcasts" makes a one-sentence briefing. roomcast's instructions tell the model to pass such a URL straight through instead of copying long item URLs.

• Routines: a scheduled agent run that starts the morning news in the bedroom.

Tools

Sonos ignores the titles roomcast sends for plain http(s) files and shows the file name (or the file's own ID3 tags) in its app. Playback is unaffected; get_queue still names each item from what roomcast remembers. Cast and DLNA show the titles.

Running it

roomcast has to run on a machine on the same LAN as the speakers that stays on: a home server, a NAS, a Raspberry Pi (64-bit OS), a Mac mini.

Docker (Linux)

Discovery is multicast (SSDP, mDNS), so the container uses host networking, which only works with Docker on Linux. Images are published for linux/amd64 and linux/arm64.

curl -O https://raw.githubusercontent.com/samoturk/roomcast-mcp/main/compose.yaml
curl -o .env https://raw.githubusercontent.com/samoturk/roomcast-mcp/main/.env.example
# edit .env, then:
docker compose up -d
docker compose logs -f roomcast

Without Docker (Linux, macOS)

With uv:

ROOMCAST_DEFAULT_ROOM=Kitchen ROOMCAST_TOKEN=$(openssl rand -hex 32) \
    uvx --from git+https://github.com/samoturk/roomcast-mcp roomcast-mcp

or uv tool install git+https://github.com/samoturk/roomcast-mcp for a permanent install. On macOS, allow "Local Network" access for your terminal when asked, or discovery finds nothing.

Connecting a client

Pick the setup that matches the client:

• Claude Code, Cursor and other clients that can send a header, on your LAN or tailnet: set ROOMCAST_HOST=0.0.0.0 and ROOMCAST_TOKEN, then add

  claude mcp add --transport http roomcast http://<machine>:8765/mcp \
      --header "Authorization: Bearer <token>"

• A client on the same machine (Claude Desktop on the Mac mini that runs roomcast): run it over stdio, no network at all:

  { "mcpServers": { "roomcast": { "command": "uvx",
      "args": ["--from", "git+https://github.com/samoturk/roomcast-mcp", "roomcast-mcp", "--stdio"],
      "env": { "ROOMCAST_DEFAULT_ROOM": "Kitchen" } } } }

• claude.ai and the Claude mobile app: custom connectors connect from Anthropic's servers and cannot send a token, so roomcast needs a public HTTPS URL with a secret path. With Tailscale Funnel:

  1. Set ROOMCAST_PATH_SECRET=$(openssl rand -hex 16).

  2. Either run tailscale funnel --bg 8765 on the host, or use the sidecar: create a tagged auth key, set TS_AUTHKEY, and docker compose --profile tailscale up -d. Funnel has to be allowed for the node in the tailnet policy (nodeAttrs → funnel).

  3. Set ROOMCAST_PUBLIC_HOST to the *.ts.net name and restart; that turns on the Host-header check.

  4. claude.ai → Settings → Connectors → Add custom connector → https://<host>.ts.net/<secret>/mcp, no authentication. It then works in the phone app too.

  When you upgrade roomcast and its tools change, disconnect and reconnect the connector and start a new chat: claude.ai keeps the tool list it fetched when it connected.

Configuration

All settings are environment variables (.env with Docker Compose).

Security

Whoever can reach the endpoint can play, queue and stop audio on your speakers. They can make roomcast fetch public URLs, and nothing else: it holds no credentials and reaches no other service. So does a web page or a feed that talks your model into calling it.

• Token or secret path. With neither set roomcast logs a warning: anyone who reaches the port controls your speakers. With ROOMCAST_PUBLIC_HOST set it refuses to start without one. Prefer ROOMCAST_TOKEN wherever the client can send it. The secret path exists for chat connectors that cannot; treat that URL like a password.

• Public addresses only. Every URL is someone else's, so roomcast fetches and plays only public http(s) addresses: each redirect hop is checked, and anything resolving to a private, loopback or link-local address (including one wrapped in NAT64, 6to4 or IPv4-mapped IPv6), or using a Sonos-internal URI scheme, is refused or dropped. That also means media servers on your LAN (Jellyfin, Navidrome, a NAS) cannot be played yet.

• What the check cannot cover. It resolves each host before connecting, and the HTTP client resolves it again to connect: a hostile DNS server answering differently the second time (DNS rebinding) can still point roomcast's request at your LAN. The speakers also look up and fetch every URL themselves, which roomcast has no control over. What leaks back through roomcast is limited to lines of a response that look like playlist URLs.

• Limits. A playlist fetch is capped at 1MB and 10 seconds; at most 100 entries are taken.

Development

uv sync --group dev
uv run pytest -q
uv run ruff check src tests
npx @modelcontextprotocol/inspector   # connect to http://localhost:8765/mcp

The image is Alpine-based (~120MB): every compiled dependency ships a musl wheel for both architectures, and protobuf runs its pure-Python implementation.

License

MIT