@senchabrew/elevenlabs-sfx-mcp

An MCP (Model Context Protocol) server that wraps the ElevenLabs Sound Effects API for use with Claude Code, Claude Desktop, Cowork, or any MCP-compliant client.

Generate sound effects and ambience audio from English prompts. Output is always 128 kbps MP3 for broad playback compatibility.

Installation

Add the server to your client's MCP configuration. For Claude Desktop, edit ~/Library/Application Support/Claude/claude_desktop_config.json (macOS):

{
  "mcpServers": {
    "sfx": {
      "command": "npx",
      "args": ["-y", "@senchabrew/elevenlabs-sfx-mcp"],
      "env": {
        "ELEVENLABS_API_KEY": "sk_..."
      }
    }
  }
}

Get an ElevenLabs API key at https://elevenlabs.io/app/settings/api-keys. Restart your client to load the server.

Requires Node.js 20 or later.

Tools

generate-sfx

Generate a sound effect or ambient audio and save it as a 128 kbps MP3 file (sent to ElevenLabs as output_format=mp3_44100_128).

Input:

| Field | Type | Required | Default | Description | |---|---|---|---|---| | prompt_en | string | yes | — | English prompt describing the sound (e.g. "Emergency alert notification beep, urgent"). | | duration_seconds | number | yes | — | Length in seconds. Must be > 0 and <= 22. SE typically 3, AMB typically 15. | | prompt_influence | number | no | 0.4 | 0.0–1.0. How strictly the result follows the prompt. SFX usually 0.4, AMB 0.25. | | output_path | string | yes | — | Absolute path where the MP3 will be written. Parent directories are auto-created. |

Output:

{ "success": true, "output_path": "/path/to/out.mp3", "duration_ms": 2345, "bytes": 48000 }

On HTTP 429, the server retries up to 3 times with a 10-second backoff before failing.

Prompt tips

The English prompt drives output quality. Concrete sensory language tends to work better than abstract description:

| ✅ Better | ❌ Worse | |---|---| | Heavy rain on metal roof, thunder in the distance | Rain ambience | | Footsteps on wet asphalt, slow pace | Walking sound | | Emergency alert siren, two-tone, urgent | Alert sound |

prompt_influence:

• 0.4–0.6 for short SFX (impacts, beeps, alerts)
• 0.2–0.3 for longer AMB (rain, crowd, room tone) — leaves room for natural variation

Output format

Fixed at 128 kbps MP3, 44.1 kHz, stereo. The bitrate is hard-coded to ensure playback compatibility with downstream tools that reject low-bitrate streams.

If you need other formats, convert downstream (e.g. with ffmpeg).

License

MIT