Simple MCP Server With Python

🚀 Building a Simple Server with Python MCP SDK

In this tutorial, we'll use the Model Context Protocol (MCP) Python SDK to build a simple server. We'll guide you through the process of installation, setup, and running the server step by step, and show you how to interact with it via the command line.

🚀 Quick Start

✨ Features

• Build a simple server using the MCP Python SDK.
• Demonstrate how to interact with the server through the command line.
• Show how to expand server functionality by adding tools and resources.

📦 Installation

First, we need to install the MCP Python SDK in the project environment:

pip install mcp-sdk

💻 Usage Examples

Basic Usage

Next, create a new Python file server.py and add the following code:

# server.py
from mcp import Server, StdioTransport

if __name__ == "__main__":
    # Initialize the MCP server
    server = Server()
    
    @server.tool("add")
    async def add_tool(arguments):
        a = arguments["a"]
        b = arguments["b"]
        return f"{int(a) + int(b)}"
    
    @server.resource("greeting://{name}")
    async def greeting_resource(name):
        return f"Hello, {name}!"
    
    # Use standard input and output as the default transport protocol
    transport = StdioTransport()
    server.start(transport)

Run the following command in the terminal to start the server:

python server.py

At this point, the server will run silently in the background, waiting for clients to connect and send requests.

Create another Python file client.py and add the following code to connect to the server:

# client.py
import asyncio
from mcp import Server, ClientSession, StdioServerParameters
from mcp.client.stdio import stdio_client

async def main():
    server_params = StdioServerParameters(
        command="python",
        args=["server.py"],
    )

    async with stdio_client(server_params) as (reader, writer):
        async with ClientSession(reader, writer) as session:
            await session.initialize()

            # Call the add tool
            result = await session.call_tool("add", arguments={"a": 3, "b": 4})
            print(f"Result of the addition tool: {result}")

if __name__ == "__main__":
    asyncio.run(main())

Run the following command in a different terminal window to start the client:

python client.py

The output should be:

Result of the addition tool: TextContent(type='text', text='7', annotations=None)

Advanced Usage

You can expand the server's functionality by adding more tools and resources. For example, add a calculator tool:

@server.tool("calculator")
async def calculator_tool(arguments):
    operation = arguments["operation"]
    a = int(arguments["a"])
    b = int(arguments["b"])
    
    if operation == "add":
        return a + b
    elif operation == "subtract":
        return a - b
    elif operation == "multiply":
        return a * b
    elif operation == "divide":
        return a / b
    else:
        raise ValueError("Invalid operation")

The MCP provides a command-line tool mcp-check to verify if the server is running correctly. Install and use it as follows:

pip install mcp-check
mcp-check http://localhost:1234

📚 Documentation

Frequently Asked Questions

⚠️ Important Note

Here are some common questions and answers to help you troubleshoot issues.

💡 Usage Tip

Make sure to check these FAQs if you encounter any problems during the development process.

Conclusion

Through this tutorial, we've successfully built a simple server using the MCP Python SDK and demonstrated how to add tools and resources. You can expand the functionality on this basis to build more complex systems.

By following this tutorial, you've mastered the skills to build a basic server using the MCP Python SDK. Good luck with your development!