speech-mcp-server

Local Stdio Model Context Protocol (MCP) server wrapping C# Kokoro ONNX neural text-to-speech engine with thread-clamped zero-VRAM CPU execution.

"Mind telemetry locked. Zero liability speech engine initialized."

🔊 Audio Demo Samples

1. Standard Speech & Baseline

Related MCP server: STT2TTS MCP

⚡ Key Architectural Features

• Zero GPU VRAM Overhead: Operates entirely on CPU via ONNX Runtime Execution Provider. Keeps GPU completely idle (0% load, ~50°C thermal ambient).

• Thread-Clamped CPU Execution: Throttled to 2 worker threads (intra_op_num_threads = 2, OMP_NUM_THREADS = 2) to eliminate CPU spikes while maintaining sub-200ms latency.

• Zero-Latency Neural Speech: Hardware audio output via native C# .NET 10 SpeechApp bridge.

• Kokoro ONNX Engine: High-fidelity 24kHz neural TTS with multiple voice profiles (am_adam, af_bella).

• Dynamic SSML & Prosody Parsing:

  • [pause=400ms] — Precise silence insertion.

  • [slow]...[/slow] — Reduced tempo (0.75x) for emphasis.

  • [fast]...[/fast] — Accelerated speech (1.4x).

  • [whisper]...[/whisper] — Softened vocal cadence.

  • [voice=af_bella]...[/voice] — Mid-sentence voice profile switching.

• MCP Stdio Transport: Full Model Context Protocol compatibility for AI agents and LLM tool integration.

📐 Pipeline Architecture

graph TD
    A[MCP Client / Antigravity AI] -->|Stdio Protocol| B[speech-mcp-server Node.js]
    B -->|Invokes Native Process| C[C# .NET 10 SpeechApp]
    C -->|Throttled 2-Thread Execution| D[Kokoro ONNX Python Engine]
    D -->|Synthesizes 24kHz Audio| E[Timestamped Temp WAV Buffer]
    E -->|Streams Sound| F[Workstation Hardware Output]

🚀 Quickstart

Prerequisites

• Node.js v18+

• Windows OS with .NET 10 SDK / runtime installed

• Python 3.10+ with kokoro-onnx, onnxruntime, soundfile, numpy

Build

git clone https://github.com/yavru421/speech-mcp-server.git
cd speech-mcp-server
npm install
npm run build

Configuration (MCP Client)

Add to your mcpServers settings:

{
  "speech-mcp-server": {
    "command": "node",
    "args": ["<path_to_repo>/build/index.js"]
  }
}

🔒 License

MIT