# 🔢 Concatenating Calculator MCP Server

> An MCP (Model Context Protocol) server that redefines addition — when asked to add two numbers, it concatenates them instead.

---

## 📖 Overview

This is a custom [Model Context Protocol (MCP)](https://modelcontextprotocol.io/) server that exposes an `add_numbers` tool. Rather than performing arithmetic addition, the tool concatenates the two inputs as strings.

**Example:**

```
Input:  add_numbers(3, 5)
Output: "35"
```

---

## ✨ Features

- Implements the MCP server specification
- Exposes a single `add_numbers` tool
- Concatenates two numbers as strings instead of summing them
- Compatible with any MCP-capable client (e.g. Claude for Desktop)

---

## 🚀 Getting Started

### Prerequisites

- [Node.js](https://nodejs.org/) v18+ (or your relevant runtime)
- An MCP-compatible client, such as [Claude for Desktop](https://claude.ai/download)

### Installation

1. **Clone the repository:**

   ```bash
   git clone https://github.com/yash312312/custom-mcp-server.git
   ```

2. **Install dependencies:**

   ```bash
   npm install
   ```

3. **Build the project:**

   ```bash
   npm run build
   ```

---

## 🔧 Configuration

To connect this server to **Claude for Desktop**, add the following to your `claude_desktop_config.json`:

```json
{
  "mcpServers": {
    "mcp-server": {
      "command": "node",
      "args": ["/absolute/path/to/your/build/index.js"]
    }
  }
}
```

> 💡 Replace `/absolute/path/to/your/build/index.js` with the actual path on your machine, which is the generated *build* folder inside the directory.

---

## 🛠️ Tool Reference

### `add_numbers`

Concatenates two numbers together as a string.

| Parameter | Type     | Description          |
|-----------|----------|----------------------|
| `a`       | `number` | The first number     |
| `b`       | `number` | The second number    |

**Returns:** A string containing `a` and `b` concatenated.

**Example:**

```
add_numbers(12, 34)  →  "1234"
add_numbers(0, 7)    →  "07"
```

---

## 📁 Project Structure

```
.
├── src/
│   └── index.ts        # MCP server entry point
├── build/              # Compiled output
├── package.json
└── README.md
```

---

## 🧪 Running Locally

You can test the server directly without a client:

```bash
node build/index.js
```

The server will start and await MCP-compatible input over stdio.

---

## 🤝 Contributing

Contributions, issues, and feature requests are welcome! Feel free to open a [GitHub Issue]([https://github.com/your-username/your-repo-name](https://github.com/yash312312/custom-mcp-server/issues) or submit a pull request.

---

## 📄 License

This project is licensed under the [MIT License](LICENSE).

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## 🙋 Acknowledgements

Built using the [Model Context Protocol SDK](https://github.com/modelcontextprotocol/typescript-sdk) by Anthropic.