Carbon Voice MCP Server

A Model Context Protocol (MCP) server implementation for integrating with Carbon Voice's API, providing AI assistants with comprehensive tools for voice messaging, conversations, and workspace management.

Carbon Voice: https://getcarbon.app

API: https://api.carbonvoice.app/docs

Features

• Message Management: Create, list, and retrieve voice messages, conversation messages, and direct messages
• User Operations: Search and retrieve user information
• Conversation Management: Access and manage conversations and their participants
• Folder Operations: Create, organize, move, and manage folders and their contents
• Workspace Administration: Get workspace information
• AI Actions: Run AI prompts and retrieve AI-generated responses
• Attachment Support: Add link attachments to messages

Security & Compliance

This server fully complies with MCP Security Best Practices:

• OAuth 2.1 Authentication: Secure authorization flow with proper token handling
• HTTPS Enforcement: All remote endpoints served over HTTPS
• Session Security: Cryptographically secure session management
• Input Validation: Comprehensive validation of all user inputs
• Rate Limiting: Built-in protection against abuse

For security concerns, please contact: devsupport@phononx.com

Prerequisites

For Stdio Transport (Local Installation)

Required:

1. Carbon Voice API Key - Contact the Carbon Voice development team to request your API key:

   • 📧 Contact: devsupport@phononx.com
   • 📧 Subject: "Request API key for MCP Server"

2. npx Installation - You must have npx installed on your system. npx comes bundled with Node.js (version 14.8.0 or later). If you don't have Node.js installed, you can download it from nodejs.org.

   To verify your installation, run:

   npx --version
   

For HTTP Transport (Remote)

Required:

1. Nothing! - No additional prerequisites are required. The HTTP transport version runs entirely in the cloud and uses OAuth2 authentication, so you don't need an API key or npx installed.

Configuration

Quick Overview

Client	HTTP Transport (Remote)	Stdio Transport (Local)
Cursor	✅ Recommended	✅ Available
Claude Desktop	✅ Recommended	✅ Available

HTTP Transport is recommended for easier setup and enhanced security.

For Cursor

HTTP Transport (Remote)

1. Open Cursor
2. Go to Cursor Settings > Features > Model Context Protocol
3. Add a new MCP server configuration:

{
  "mcpServers": {
    "Carbon Voice": {
      "url": "https://mcp.carbonvoice.app"
    }
  }
}

4. Save and restart Cursor

The first time you use it, Cursor will guide you through the OAuth2 authentication process.

Stdio Transport (Local Installation)

If you prefer to run the MCP server locally with API key authentication:

1. Open Cursor
2. Go to Cursor Settings > Features > Model Context Protocol
3. Add a new MCP server configuration:

{
  "mcpServers": {
    "Carbon Voice": {
      "command": "npx",
      "env": {
        "CARBON_VOICE_API_KEY": "your_api_key_here"
      },
      "args": ["-y", "@carbonvoice/cv-mcp-server"]
    }
  }
}

4. Replace "your_api_key_here" with your actual Carbon Voice API key
5. Save and restart Cursor

For Claude Desktop

HTTP Transport (Remote)

Setting up Carbon Voice in Claude Desktop is straightforward! Here's how to do it:

1. Open Claude Desktop and navigate to Search and Tools

2. Go to Manage Connectors and click "Add custom connector"

3. Fill in the connector details:

   • Name: Give it a friendly name like "Carbon Voice"
   • Remote MCP Server URL: Enter https://mcp.carbonvoice.app

4. Save your connector

5. Click Connect:

The first time you use it, Claude will guide you through the OAuth2 authentication process. You'll just need to sign in with your Carbon Voice account and grant permissions. After that, you're all set!

Stdio Transport (Local Installation)

If you prefer to run the MCP server locally with API key authentication:

1. Open your Claude Desktop configuration file:

   • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
   • Windows: %APPDATA%\Claude\claude_desktop_config.json

2. Add the Carbon Voice MCP server configuration:

{
  "mcpServers": {
    "Carbon-Voice": {
      "command": "npx",
      "env": {
        "CARBON_VOICE_API_KEY": "your_api_key_here"
      },
      "args": ["-y", "@carbonvoice/cv-mcp-server"]
    }
  }
}

3. Replace "your_api_key_here" with your actual Carbon Voice API key
4. Save the file and restart Claude Desktop

Environment Variables (Only available for Stdio Version)

When using the stdio version of the MCP server, you can configure additional environment variables:

LOG_LEVEL

Controls the verbosity of logging output. Available options:

• info (default) - Standard logging information
• debug - Most verbose logging, shows detailed request/response data
• warn - Only warning and error messages
• error - Only error messages

Example:

{
  "mcpServers": {
    "Carbon-Voice": {
      "command": "npx",
      "env": {
        "CARBON_VOICE_API_KEY": "your_api_key_here",
        "LOG_LEVEL": "debug"
      },
      "args": ["-y", "@carbonvoice/cv-mcp-server"]
    }
  }
}

LOG_DIR

Specifies the directory where log files will be stored. Defaults to: /tmp/cv-mcp-server/logs

The server will create two log files in this directory:

• combined.log - Contains all log messages
• error.log - Contains only error messages

Example:

{
  "mcpServers": {
    "Carbon-Voice": {
      "command": "npx",
      "env": {
        "CARBON_VOICE_API_KEY": "your_api_key_here",
        "LOG_DIR": "/Users/USER_NAME/Documents/cv-mcp-server/logs"
      },
      "args": ["-y", "@carbonvoice/cv-mcp-server"]
    }
  }
}

Complete Example with Both Variables:

{
  "mcpServers": {
    "Carbon-Voice": {
      "command": "npx",
      "env": {
        "CARBON_VOICE_API_KEY": "your_api_key_here",
        "LOG_LEVEL": "debug",
        "LOG_DIR": "/Users/USER_NAME/Documents/cv-mcp-server/logs"
      },
      "args": ["-y", "@carbonvoice/cv-mcp-server"]
    }
  }
}

Available Tools

Messages

• list_messages - List messages with date filtering (max 31-day range)
• get_message - Retrieve a specific message by ID
• get_recent_messages - Get the 10 most recent messages with full context
• create_conversation_message - Send a message to a conversation
• create_direct_message - Send direct messages to users or groups
• create_voicememo_message - Create voice memo messages
• add_attachments_to_message - Add link attachments to existing messages

Users

• get_user - Retrieve user information by ID
• search_user - Find a user by phone number or email
• search_users - Search multiple users by various identifiers

Conversations

• list_conversations - Get all conversations from the last 6 months
• get_conversation - Retrieve conversation details by ID
• get_conversation_users - Get all users in a conversation

Folders

• get_workspace_folders_and_message_counts - Get folder and message statistics
• get_root_folders - List root folders for a workspace
• create_folder - Create new folders
• get_folder - Retrieve folder information
• get_folder_with_messages - Get folder with its messages
• update_folder_name - Rename folders
• delete_folder - Delete folders (⚠️ destructive operation)
• move_folder - Move folders between locations
• move_message_to_folder - Organize messages into folders

Workspace

• get_workspaces_basic_info - Get basic workspace information

AI Actions

• list_ai_actions - List available AI prompts/actions
• run_ai_action - Execute AI actions on messages
• run_ai_action_for_shared_link - Run AI actions on shared content
• get_ai_action_responses - Retrieve AI-generated responses

Usage Examples

Getting Started

After configuration, you can interact with Carbon Voice through your AI assistant. Here are some example requests:

"Show me my recent messages"
"Create a voice memo about today's meeting"
"Search for user john@example.com"
"Show me my workspace information"
"List my conversations from this week"

Working with Folders

"Create a folder called 'Project Updates'"
"Move message ID 12345 to the Project Updates folder"
"Show me all messages in the Marketing folder"

AI Actions

"Run a summary AI action on message ID 67890"
"List all available AI prompts"
"Get AI responses for conversation ID 123"

Error Handling

The server includes comprehensive error handling and logging. Errors are returned in a structured format that includes:

• Error messages
• HTTP status codes
• Request context
• Debugging information

Development

This section is for developers who want to contribute, implement new features, or fix issues.

Development Commands

Building and Development

npm run build          # Build the project
npm run auto:build     # Watch mode with auto-rebuild (recommended for development)
npm run lint:fix       # Fix linting issues

API Generation

npm run generate:api   # Generate TypeScript types from Carbon Voice API

Running the Server

npm run dev:http       # Start HTTP server in development mode with hot reload
npm run start:http     # Start HTTP server in production mode

Testing with MCP Inspector

Setup: Copy .env.sample to .env and configure your development environment variables.

npm run mcp:inspector:stdio  # Test stdio transport with MCP Inspector
npm run mcp:inspector:http   # Test HTTP transport with MCP Inspector

For stdio transport testing:

1. Open the generated URL with token (e.g., http://localhost:6274/?MCP_PROXY_AUTH_TOKEN=46bfbd8938955be26da7f2089a8cccb7be57ed570e65d8d2d68e95561ed9b79e)
2. Set Transport Type: STDIO
3. Set Command: node
4. Click Connect
5. Should see Connected info.

For HTTP transport testing:

1. Open the generated URL with token
2. Set Transport Type: Streamable HTTP
3. Set URL: http://localhost:3005
4. Click Auth, then Quick Oauth Flow.
5. Will be redirected to Carbon Voice Auth Page. After Login, Bearer token should be auto added to Authorization Request headers.
6. Click Connect
7. Should see Connected info.

Version Management

Note: Only code merged to main branch with a different version from the current one will create a new Git tag and trigger a new npm package release. The CI/CD pipeline automatically checks if the version in package.json has changed before deploying and publishing.

Version Commands

npm run version:patch  # Bump patch version (1.0.0 → 1.0.1)
npm run version:minor  # Bump minor version (1.0.0 → 1.1.0)
npm run version:major  # Bump major version (1.0.0 → 2.0.0)

Release Commands

npm run release:patch  # Build, test, version patch, and merge to main
npm run release:minor  # Build, test, version minor, and merge to main
npm run release:major  # Build, test, version major, and merge to main
npm run deploy:release # Build, test, and merge to main (no version bump)

Development Workflow Examples

Commit to Develop

# 1. Make your changes and test locally
npm run build
npm run lint:fix

# 2. Commit and push to develop
git add .
git commit -m "feat: add new message filtering feature"
git push origin develop

Release Bug Fix

# 1. Test your changes
npm run build
npm run mcp:inspector:http

# 2. Release patch version
npm run release:patch

Release New Feature

# 1. Test your changes
npm run build
npm run mcp:inspector:stdio
npm run mcp:inspector:http

# 2. Release minor version
npm run release:minor

Development Tips

• Use auto:build during development for automatic rebuilding when files change
• Test both transports with MCP Inspector before releasing
• Run generate:api when Carbon Voice API changes
• Use semantic versioning: patch for fixes, minor for features, major for breaking changes
• Always test with both stdio and HTTP transports before releasing

MCP Compliance

This server is fully compliant with the Model Context Protocol specification and follows all security best practices outlined in the official documentation. The implementation supports both stdio and HTTP transports as defined in the MCP specification.

Support

• Issues: GitHub Issues
• API Key Requests: devsupport@phononx.com
• Carbon Voice Platform: https://getcarbon.app
• API Documentation: https://api.carbonvoice.app/docs

License

ISC License - See LICENSE file for details.

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Note: This MCP server requires a valid Carbon Voice API key to function with stdio transport. For HTTP transport, OAuth2 authentication is handled automatically through the web interface. Please ensure you have the appropriate credentials before attempting to use the server.