Example: Sheet Music Server

A demo MCP App that renders ABC notation as sheet music with interactive audio playback using the abcjs library.

MCP Client Configuration

Add to your MCP client configuration (stdio transport):

{
  "mcpServers": {
    "sheet-music": {
      "command": "npx",
      "args": [
        "-y",
        "--silent",
        "--registry=https://registry.npmjs.org/",
        "@modelcontextprotocol/server-sheet-music",
        "--stdio"
      ]
    }
  }
}

Local Development

To test local modifications, use this configuration (replace ~/code/ext-apps with your clone path):

{
  "mcpServers": {
    "sheet-music": {
      "command": "bash",
      "args": [
        "-c",
        "cd ~/code/ext-apps/examples/sheet-music-server && npm run build >&2 && node dist/index.js --stdio"
      ]
    }
  }
}

Features

• Audio Playback: Built-in audio player with play/pause and loop controls
• Sheet Music Rendering: Displays ABC notation as properly formatted sheet music

Running

1. Install dependencies:

   npm install

2. Build and start the server:

   npm run start:http  # for Streamable HTTP transport
   # OR
   npm run start:stdio  # for stdio transport

3. View using the basic-host example or another MCP Apps-compatible host.

Tool Input

When calling the play-sheet-music tool, provide ABC notation:

{
  "abcNotation": "X:1
T:C Major Scale
M:4/4
L:1/4
K:C
C D E F | G A B c |"
}

ABC Notation Examples

C Major Scale:

X:1
T:C Major Scale
M:4/4
L:1/4
K:C
C D E F | G A B c |

Twinkle, Twinkle Little Star:

X:1
T:Twinkle, Twinkle Little Star
M:4/4
L:1/4
K:C
C C G G | A A G2 | F F E E | D D C2 |
G G F F | E E D2 | G G F F | E E D2 |
C C G G | A A G2 | F F E E | D D C2 |

Architecture

Server (server.ts)

Exposes a single play-sheet-music tool that accepts:

• abcNotation: ABC notation string to render

The tool validates the ABC notation server-side using the abcjs parser and returns any parse errors. The actual rendering happens client-side when the UI receives the tool input.

App (src/mcp-app.ts)

• Receives ABC notation via ontoolinput handler
• Uses abcjs for audio playback controls and sheet music rendering (in renderAbc())