VoiceOver MCP Server

Text-to-speech server exposing one MCP tool (voice_over) over SSE, plus a matching REST API. Audio is generated to a temp directory (safe for ephemeral disks on Render/Railway/Fly/etc.) and served back over HTTP so any LLM client or frontend can render it.

Project layout

app/
├── main.py              # FastAPI app factory: middleware, lifespan, routers
├── config.py             # all env-var configuration in one place
│
├── models/
│   └── schemas.py         # TTSRequest / TTSResponse Pydantic models
│
├── core/                    # transport-agnostic business logic
│   ├── tts.py                 # edge-tts wrapper (generate_audio_core, list_available_voices)
│   ├── files.py                 # filename generation, temp-path resolution, cleanup
│   └── logging.py                 # in-memory request log
│
├── mcp/                              # MCP protocol layer
│   ├── server.py                       # Server("voiceover-mcp-server") instance
│   ├── tools.py                          # tool schema: single "voice_over" tool
│   └── handlers.py                         # call_tool dispatch -> core.tts
│
├── routes/                                    # REST layer (one file per resource)
│   ├── root.py                                  # GET / , GET /health
│   ├── mcp_sse.py                                 # GET /mcp/sse
│   ├── tts.py                                       # POST /api/v1/tts
│   ├── voices.py                                      # GET /api/v1/voices
│   ├── audio.py                                         # GET /api/v1/audio/{filename}
│   └── logs.py                                            # GET /api/v1/logs
│
└── utils/
    └── formatting.py                                        # file-size + timestamp helpers

tests/                                                            # pytest suite (27 tests)
run.py                                                              # entry point

Related MCP server: edge-tts

Run it

pip install -r requirements.txt
cp .env.example .env   # edit as needed
python run.py

Server starts on http://0.0.0.0:8080 by default. Docs at /docs.

The voice_over MCP tool

Connect an MCP client to GET /mcp/sse. The single exposed tool:

• Input: text (required), voice, rate, pitch, volume, output_filename

• Output: { "success": true, "content": "<original text>", "filename": "<name>.mp3", "timestamp": "..." }

The tool does not return audio bytes or a filesystem path — only the filename. Fetch the actual file with:

GET /api/v1/audio/{filename}

This is what your deploy/render layer should call to play or download the generated clip.

REST API (mirrors the MCP tool 1:1)

Storage model

• All audio is written to a single ephemeral temp directory (TEMP_DIR, defaults to the OS temp dir + voiceover_mcp).

• Filenames are sanitized and resolved with Path(...).name only — no path traversal via output_filename or the download route.

• AUDIO_TTL_SECONDS (default 1 hour) controls a startup cleanup sweep that deletes stale files.

• Because storage is ephemeral, files will not survive a server restart on most PaaS platforms — by design. The download endpoint returns a clear 404 if a file has expired or the instance was recycled.

Testing

python -m pytest tests/ -v

27 tests covering: filename/path safety, TTS core logic (edge-tts mocked, no real network calls), the MCP voice_over tool handler, and all REST routes.

Environment variables

See .env.example. Key ones:

• PORT, HOST — server binding

• TEMP_DIR — override the audio temp directory

• AUDIO_TTL_SECONDS — cleanup age threshold

• DEFAULT_VOICE, DEFAULT_RATE, DEFAULT_PITCH, DEFAULT_VOLUME — TTS defaults