Upnext

upnext-mcp

An MCP server for your machine's audio. One queue across Spotify, the browser, local files, and whatever is already playing.

{

"mcpServers": { "upnext": { "command": "npx", "args": ["-y", "upnext-mcp", "--library", "/Users/me/Music"] } } }

Drop that in Claude Desktop, Cursor, Windsurf, or anything else that speaks MCP.

What it lets an agent do

you:  what am I listening to?

→ ❚❚ Acquired — Jensen Huang (Google Chrome)

you: let that finish, then play Bad Habit → adopted "Acquired — Jensen Huang" as q_0001 up next: q_0001 Acquired — Jensen Huang q_0002 Bad Habit — Steve Lacy

The first line reads a browser tab — no extension. The second puts it in the queue as a real entry, so the agent adds to what someone is doing rather than cutting across it.

Tools

Every mutation is addressed by id, and every response includes the queue with ids in it. That's deliberate: a model working from positions races anything else touching the queue, and by the time its call lands, position 2 is a different song.

It tells the model the truth

Two places where this behaves differently from most tool servers, both for the same reason — a model that gets a silent no-op will confidently tell the user it worked.

`media_seek` on a source that can't seek returns a sentence, not an error:

the current source (spotify-desktop) cannot seek. Nothing changed.

`media_search` with nothing wired to search explains itself:

nothing found for "bad habit".

playing through: spotify-desktop, nowplaying, local

titles will NOT resolve: nothing wired here can search…

Titles need a searcher

A link says exactly what to play. A *description* has to be looked up, and not every backend can. The Spotify desktop app plays a URI you hand it but cannot search a catalogue — so on a plain Mac setup, media_enqueue with "bad habit" has nothing to resolve against.

Give it one of these:

// index a music folder

"args": ["-y", "upnext-mcp", "--library", "/Users/me/Music"]

// or a Spotify Web token, via the environment "env": { "SPOTIFY_TOKEN": "..." }

media_setup will tell you which you have.

Embedding it instead

If your product already has a queue, expose *that* one rather than starting a second that competes with it:

import { createServer } from 'upnext-mcp';

import { serveStdio } from '@modelcontextprotocol/server/stdio';

serveStdio(() => createServer(myExistingRuntime));

This package is a transport, and nothing more — ordering, capability negotiation, resolution and reconciliation all happen in upnext-core. It lives apart because a transport is an opinion, and nobody importing the runtime should inherit this one.

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Full docs: https://github.com/tothienbao6a0/upnext · Apache-2.0