Create MCP Server

🚀 Creating a Custom Server

Start building your own server for use in Claude for Desktop and other clients.

In this tutorial, we'll build a simple MCP calculator server and connect it to the host, Claude for Desktop.

What is MCP?

MCP stands for Model Context Protocol – it's a protocol that allows developers to extend the capabilities of AI assistants (such as Claude) with custom tools and servers.

• Think of it as adding extra functionality to your AI assistant.
• These servers provide functions or features that the assistant can call during a conversation.
• For example, you can build a weather server, a calculator, a financial assistant, or anything else you can imagine.

What We're Building

We'll build a server that offers four tools: add, subtract, multiply, and divide. Then we'll connect this server to an MCP host (Claude for Desktop in this example):

⚠️ Important Note

The server can be connected to any client. We've chosen Claude for Desktop for demonstration purposes.

System Requirements

• Operating System: MacOS, Linux, or Windows
• Python: 3.6+
• uv Tool: Used to run the server

📦 Installation

MacOS/Linux

# Clone the repository
git clone https://github.com/your-repository.git
cd calculator-server

# Create and activate a virtual environment
python -m venv env
source env/bin/activate  # MacOS/Linux

Windows

# Clone the repository
git clone https://github.com/your-repository.git
cd calculator-server

# Create and activate a virtual environment
python -m venv env
env\Scripts\activate  # Windows

Project Structure

calculator-server/
├── calculator.py       # Main server file
└── README.md          # Project description

Running the Server

MacOS/Linux

uv --directory ./ run calculator.py

Windows

uv --directory .\ run calculator.py

Configuring Claude for Desktop

To make the calculator server available in Claude for Desktop, you need to edit Claude's configuration file.

MacOS/Linux

code ~/Library/Application\ Support/Claude/claude_desktop_config.json

Windows

code $env:AppData\Claude\claude_desktop_config.json

In this file, add the following content:

MacOS/Linux

{
    "mcpServers": {
        "calculator": {
            "command": "/path/to/uv",
            "args": [
                "--directory",
                "/ABSOLUTE/PATH/TO/PARENT/FOLDER/calculator-server",
                "run",
                "calculator.py"
            ]
        }
    }
}

Windows

{
    "mcpServers": {
        "calculator": {
            "command": "C:\path\to\uv.exe",
            "args": [
                "--directory",
                "C:\\ABSOLUTE\\PATH\\TO\\PARENT\\FOLDER\\calculator-server",
                "run",
                "calculator.py"
            ]
        }
    }
}

⚠️ Important Note

Replace /path/to/uv with the actual path to the uv executable file.

After saving the file, restart Claude for Desktop to see the new calculator tool.

💻 Usage Examples

Basic Usage

Addition

claude> add 10 20
30

Subtraction

claude> subtract 50 30
20

Multiplication

claude> multiply 10 5
50

Division

claude> divide 100 20
5

📚 Documentation

For more information, refer to the MCP official documentation.