voicebox/backend/mcp_server

Voicebox MCP server

Local Model Context Protocol server — lets any MCP-aware agent (Claude Code, Cursor, Windsurf, VS Code MCP extensions, etc.) speak text in your cloned voices, transcribe audio, and browse captures.

The server runs inside the same uvicorn process as the rest of Voicebox and is mounted at /mcp (Streamable HTTP transport).

Install into your agent

Preferred — direct HTTP:

{
  "mcpServers": {
    "voicebox": {
      "url": "http://127.0.0.1:17493/mcp",
      "headers": { "X-Voicebox-Client-Id": "claude-code" }
    }
  }
}

Fallback — stdio shim (when the client doesn't speak HTTP MCP). The voicebox-mcp binary ships inside the Voicebox.app bundle:

{
  "mcpServers": {
    "voicebox": {
      "command": "/Applications/Voicebox.app/Contents/MacOS/voicebox-mcp",
      "env": { "VOICEBOX_CLIENT_ID": "claude-code" }
    }
  }
}

Claude Code one-liner:

claude mcp add voicebox \
  --transport http \
  --url http://127.0.0.1:17493/mcp \
  --header "X-Voicebox-Client-Id: claude-code"

Tools

Name	Purpose
voicebox_speak	Speak text in a voice profile. Returns a generation id you can poll.
voicebox_transcribe	Whisper transcription of a base64 blob or an absolute local path.
voicebox_list_captures	Recent captures (dictation / recording / file) with transcripts.
voicebox_list_profiles	Available voice profiles (cloned + preset).

All tools resolve voice profiles in this precedence:

1. Explicit profile arg (name or id — case-insensitive)
2. Per-client binding keyed by X-Voicebox-Client-Id
3. capture_settings.default_playback_voice_id (global default)

Bindings are managed via GET|PUT /mcp/bindings or in the app under Settings → MCP.

Debug with MCP Inspector

npx @modelcontextprotocol/inspector http://127.0.0.1:17493/mcp

Point it at the URL, hit "List tools," call voicebox_list_profiles first to confirm wiring, then voicebox_speak for end-to-end.

Non-MCP REST surface

POST /speak is a thin wrapper on the same code path for callers that don't speak MCP (shell scripts, ACP, A2A):

curl -X POST http://127.0.0.1:17493/speak \
  -H 'Content-Type: application/json' \
  -H 'X-Voicebox-Client-Id: claude-code' \
  -d '{"text":"Build complete.","profile":"Morgan"}'

Code layout

backend/mcp_server/
├── __init__.py      # re-export mount_into
├── server.py        # build_mcp_server() + mount_into(app)
├── tools.py         # @mcp.tool() implementations
├── context.py       # ClientIdMiddleware + current_client_id ContextVar
├── resolve.py       # profile resolution precedence
├── events.py        # pub/sub queue for /events/speak pill SSE
└── README.md        # you are here

backend/mcp_shim/    # stdio ↔ Streamable-HTTP proxy (see its README)

The package is mcp_server, not mcp, to avoid shadowing the installed mcp PyPI package that FastMCP imports internally.