Voice Transcriber MCP Server

MCP server that automatically transcribes Google Chat voice messages using Groq Whisper API (whisper-large-v3). No local GPU needed.

When Claude Code encounters an audio attachment in a Google Chat message, this server transcribes it immediately without asking for confirmation.

Features

• Transcribe Google Chat voice messages by URL (automatic)
• Transcribe local audio files (mp3, m4a, wav, ogg, flac, webm, aac)
• Uses Groq Whisper API (free tier, fast, cloud-based)
• Reuses Google Chat OAuth2 credentials (no separate Google auth needed)

Prerequisites

1. Groq API Key (free)

1. Go to console.groq.com/keys
2. Create a free account
3. Generate an API key
4. You'll set this as GROQ_API_KEY in your MCP config (see below)

2. Google Chat OAuth2 Token

This server needs a valid Google Chat OAuth2 token (token.json) to fetch messages and download audio attachments.

If you already use a Google Chat MCP server (e.g. multi-chat-mcp-server), the token is already available. Default path:

~/tools/multi-chat-mcp-server/src/providers/google_chat/token.json

If your token is in a different location, set the GCHAT_TOKEN_PATH environment variable.

If you don't have a Google Chat token yet, you need to:

1. Create a Google Cloud project with Chat API enabled
2. Create OAuth2 credentials (Desktop app)
3. Run the OAuth flow to generate token.json with scopes:
   • https://www.googleapis.com/auth/chat.messages.readonly
   • https://www.googleapis.com/auth/chat.spaces.readonly

3. uv (Python package manager)

OS	Command
Linux / macOS / WSL	curl -LsSf https://astral.sh/uv/install.sh | sh
Windows	powershell -c "irm https://astral.sh/uv/install.ps1 | iex"

Verify: uv --version

Installation

git clone https://github.com/fgasparetto/voice-transcriber-mcp.git
cd voice-transcriber-mcp
uv sync

Configuration

Add to your Claude Code MCP config (.mcp.json or ~/.claude.json):

{
  "mcpServers": {
    "voice-transcriber": {
      "type": "stdio",
      "command": "uv",
      "args": [
        "--directory", "/path/to/voice-transcriber-mcp",
        "run", "python", "server.py"
      ],
      "env": {
        "GROQ_API_KEY": "gsk_your_groq_api_key_here"
      }
    }
  }
}

Replace:

• /path/to/voice-transcriber-mcp with the actual clone directory
• gsk_your_groq_api_key_here with your Groq API key

Environment Variables

Variable	Required	Default	Description
GROQ_API_KEY	Yes	—	Groq API key (get one free)
GCHAT_TOKEN_PATH	No	~/tools/multi-chat-mcp-server/src/providers/google_chat/token.json	Path to Google Chat OAuth2 token

Tools

transcribe_voice_message

Transcribe a voice message from Google Chat. Called automatically by Claude when it encounters an audio attachment.

transcribe_voice_message(
  message_url="https://chat.google.com/dm/SPACE/THREAD/MSG",
  language="it"
)

transcribe_audio_file

Transcribe a local audio file.

transcribe_audio_file(
  file_path="/tmp/recording.m4a",
  language="it"
)

Platform Notes

Linux

No additional steps. Ensure uv is in your PATH.

macOS

• If uv not found after install: export PATH="$HOME/.local/bin:$PATH"

Windows (WSL)

Claude Code runs inside WSL. All paths must be Linux-style:

• Token path: /home/USER/tools/... (NOT /mnt/c/...)
• If uv not found: source ~/.bashrc or add ~/.local/bin to PATH

Troubleshooting

Problem	Solution
GROQ_API_KEY not set	Add it to the env section in your MCP config
Google Chat token not found	Set GCHAT_TOKEN_PATH or authenticate your Google Chat MCP
Groq API error 413	Audio file too large (Groq limit: 25MB)
uv: command not found	Install uv (see Prerequisites)

How It Works

Claude Code → MCP tool call → server.py
  1. Parse Google Chat URL
  2. Fetch message via Google Chat API (OAuth2 token)
  3. Download audio attachment via media API
  4. Send to Groq Whisper API (whisper-large-v3)
  5. Return transcribed text

License

MIT