📡 Remote Communication MCP Server

A production-ready Model Context Protocol (MCP) server built with Node.js and TypeScript that exposes email communication tools over HTTP/SSE Transport (using StreamableHTTPServerTransport).

This remote implementation allows AI clients like Claude Desktop, Cursor, or MCP Inspector to connect to a publicly hosted instance (e.g., deployed on Render) rather than running the process locally.

---

📖 What is MCP?

The Model Context Protocol (MCP) is an open standard that enables AI applications to connect to external tools and data sources. While local MCP servers run as child processes over stdio, remote MCP servers expose a web server communicating over JSON-RPC streamed via HTTP Server-Sent Events (SSE).

┌──────────────────┐            HTTP / SSE            ┌─────────────────────┐
│    AI Client     │ ◄──────────────────────────────► │  Remote MCP Server  │
│ (Claude/Cursor/  │        JSON-RPC over POST        │    (This Project)   │
│  MCP Inspector)  │      & Event Stream (GET)        │                     │
└──────────────────┘                                  └─────────────────────┘

---

🏗️ Architecture

┌────────────────────────────────────────────────────────────────────────┐
│                                AI Client                               │
│                  (Claude Desktop / Cursor / Inspector)                 │
└───────────────────┬───────────────────────────────▲────────────────────┘
                    │                               │
                    │ HTTP POST /mcp                │ GET /mcp (SSE Stream)
                    ▼                               │
┌───────────────────────────────────────────────────┴────────────────────┐
│                  Remote MCP Server (Express / Node.js)                 │
│                                                                        │
│   ┌───────────────────────────────────────────────────────────────┐    │
│   │                     Active Sessions Store                     │    │
│   │             Maps: Session ID ──► MCP Server Session           │    │
│   │                                                               │    │
│   │ ┌───────────────────────────────────────────────────────────┐ │    │
│   │ │                     MCP Server Session                    │ │    │
│   │ │  ┌──────────────────────────────────────────────────────┐ │ │    │
│   │ │  │                   Streamable Transport               │ │ │    │
│   │ │  └──────────────────────────┬───────────────────────────┘ │ │    │
│   │ │                             ▼                             │ │    │
│   │ │  ┌──────────────────────────────────────────────────────┐ │ │    │
│   │ │  │                     McpServer                        │ │ │    │
│   │ │  │ ┌──────────────┐ ┌────────────────┐ ┌──────────────┐ │ │ │    │
│   │ │  │ │ health_check │ │ list_providers │ │  send_email  │ │ │ │    │
│   │ │  │ └──────────────┘ └────────────────┘ └───────┬──────┘ │ │ │    │
│   │ │  └─────────────────────────────────────────────┼────────┘ │ │    │
│   │ └────────────────────────────────────────────────┼──────────┘ │    │
│   └──────────────────────────────────────────────────┼────────────┘    │
│                                                      │                 │
│                                         ┌────────────▼─────────────┐   │
│                                         │     EmailService         │   │
│                                         │     (Nodemailer)         │   │
│                                         └────────────┬─────────────┘   │
└──────────────────────────────────────────────────────┼─────────────────┘
                                                       │
                                                       ▼
                                          ┌──────────────────────────┐
                                          │      SMTP Server         │
                                          │  (Gmail, Outlook, etc.)  │
                                          └──────────────────────────┘

---

📁 Project Structure

communication-mcp-server/
├── src/
│   ├── server.ts              # Entry point — Express + Streamable HTTP Server
│   ├── config/
│   │   └── index.ts           # Environment configuration loader
│   ├── tools/
│   │   ├── index.ts           # Tool registry (registers all tools)
│   │   ├── health.tool.ts     # health_check tool
│   │   ├── providers.tool.ts  # list_providers tool
│   │   └── email.tool.ts      # send_email tool
│   ├── services/
│   │   └── email.service.ts   # Email delivery via Nodemailer
│   ├── utils/
│   │   ├── logger.ts          # Pino logger (writes to stderr)
│   │   └── validators.ts      # Email validation utilities
│   └── types/
│       └── index.ts           # TypeScript type definitions
├── .env.example               # Environment variable template
├── .gitignore                 # Git ignore rules
├── package.json               # Dependencies & scripts
├── render.yaml                # Render.com deployment blueprint
├── tsconfig.json              # TypeScript configuration
└── README.md                  # This file

---

🛠️ Available Endpoints & Tools

HTTP Endpoints

• GET /health - Public endpoint returning server configuration and status.
• POST /mcp - MCP JSON-RPC message endpoint.
• GET /mcp - MCP Server-Sent Events (SSE) stream endpoint.
• DELETE /mcp - Terminates the MCP session.

Registered MCP Tools

Tool	Description	Parameters
health_check	Returns server status, timestamp, version, and uptime	None
list_providers	Lists configured communication providers	None
send_email	Sends an email via SMTP	to, subject, text, html?

---

🚀 Installation

Prerequisites

• Node.js >= 18.0.0
• npm >= 9.0.0
• An SMTP email account (e.g., Gmail with App Password)

Setup

# 1. Clone the repository
git clone https://github.com/your-username/communication-mcp-server.git
cd communication-mcp-server

# 2. Install dependencies
npm install

# 3. Configure environment variables
cp .env.example .env
# Edit .env with your SMTP credentials, PORT, and optional API_KEY

# 4. Build the project
npm run build

---

⚙️ Configuration

Copy .env.example to .env and fill in your values:

Variable	Description	Default / Example
NODE_ENV	Environment mode	development
LOG_LEVEL	Pino log level (debug, info, warn, error)	info
PORT	HTTP Server port	3000
API_KEY	Optional token to secure the MCP endpoints	(None)
CORS_ORIGIN	CORS allowed origins	*
SMTP_HOST	SMTP server hostname	smtp.gmail.com
SMTP_PORT	SMTP server port	587
SMTP_SECURE	Use TLS (true for port 465)	false
SMTP_USER	SMTP authentication username	—
SMTP_PASS	SMTP authentication password (Gmail App Password)	—
SMTP_FROM	Default sender address	—

---

🏃 Running Locally

Development Mode (with hot reload)

npm run dev

Production Mode

npm run build
npm start

---

🔌 Connecting to the Server

Remote HTTP MCP servers require a client that supports HTTP/SSE transport.

1. Connecting via Claude Desktop

Claude Desktop natively supports remote MCP servers. Add the server under the mcpServers object using the sse type:

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

{
  "mcpServers": {
    "communication-remote": {
      "url": "https://your-app-name.onrender.com/mcp",
      "headers": {
        "Authorization": "Bearer your-optional-api-key"
      }
    }
  }
}

Note: Replace https://your-app-name.onrender.com/mcp with your actual local or deployed URL (e.g. http://localhost:3000/mcp for local testing).

2. Connecting via Cursor

Cursor supports connecting to remote MCP servers using the SSE server type:

1. Open Cursor Settings → Features → MCP.
2. Click + Add New MCP Server.
3. Fill in the options:
   • Name: communication-remote
   • Type: SSE
   • URL: https://your-app-name.onrender.com/mcp

If you secured your server with an API_KEY, make sure you configure your client or URL to pass the authorization header or use URL query params like https://your-app-name.onrender.com/mcp?api_key=your-key.

3. Connecting via MCP Inspector

Verify your remote server's functionality visually using the MCP Inspector:

npx @modelcontextprotocol/inspector http://localhost:3000/mcp

(Add headers if API key authentication is enabled)

---

🚢 Deployment to Render

The repository contains a render.yaml blueprint to quickly deploy this project as a Web Service on Render.

1. Push your code to a Git repository (GitHub/GitLab).
2. Go to your Render Dashboard.
3. Click New + → Blueprint.
4. Select your connected repository.
5. Configure the environment variables (SMTP_HOST, SMTP_USER, SMTP_PASS, API_KEY, etc.) in the Render UI.
6. Click Deploy.

Render will build and deploy the application, setting up an HTTPS endpoint automatically (e.g. https://communication-mcp-server.onrender.com).

---

🔮 Future Improvements

• [ ] SMS Integration — Add SMS support via Twilio or other professional SMS API gateway.
• [ ] Rate Limiting — Add Express rate limiter middleware to prevent spam/abuse on the public route.
• [ ] Persistent Session Stores — Move active sessions from in-memory map to Redis to allow multi-instance auto-scaling.
• [ ] JWT Authentication — Implement OAuth2/JWT-based authorization for multi-tenant users.
• [ ] Message History — Database integration to track email history and delivery logs.

---

📄 License

MIT