Create an MCP Server with .NET and C#

#mcp #csharp #dotnet #openai

In this post, I'll show you how to create a simple MCP Server and test it in Cursor.

For this tutorial, I'm using the official csharp-sdk, which is still in its early stages:

https://github.com/modelcontextprotocol/csharp-sdk

1. Create a simple project

First, create an empty console project:

dotnet new console -n Tutorial.McpTimeServer

2. Install packages

Install these 2 packages:

dotnet add package Microsoft.Extensions.Hosting
dotnet add package ModelContextProtocol --prerelease

3. Write the code

Replace the Program.cs content with this:

using System.ComponentModel;
using Microsoft.Extensions.Hosting;
using ModelContextProtocol;
using ModelContextProtocol.Server;

Console.WriteLine("Hello MCP World!");

var builder = Host.CreateEmptyApplicationBuilder(settings: null);

builder.Services
       .AddMcpServer()
       .WithStdioServerTransport()
       .WithTools();

var host = builder.Build();
await host.RunAsync();


[McpToolType]
public static class TimeTool
{
    [McpTool, Description("Gets the current time.")]
    public static string GetCurrentTime() => DateTimeOffset.Now.ToString();
}

4. Run the project

If you run the project using dotnet run, you will see Hello MCP World! and the program will remain open as it's listening to stdin.

5. Test it on Cursor

Now it's time to configure it on Cursor. Go to File -> Preferences -> Cursor Settings.

Click on "Add new global MCP Server" or open .cursor/mcp.json and add your MCP Server information like this:

{
  "mcpServers": {
    "timemcp": {
      "command": "cmd",
      "args": [
        "/c",
        "C:/Users/Mehran/source/repos/Tutorial.McpTimeServer/bin/Debug/net9.0/Tutorial.McpTimeServer.exe"
      ]
    }
  }
}