Build your MCP Server using C# SDK

What is Build your MCP Server using C# SDK?

This is an educational .NET console application that creates a simple MCP server with three string‑manipulation tools (echo, reverse, length). It is designed to show developers how to build a custom MCP server using the official Microsoft C# SDK and integrate it with GitHub Copilot (Agent mode) as the client.

How to use Build your MCP Server using C# SDK?

Create a .NET console application, add NuGet packages Microsoft.Extensions.Hosting and ModelContextProtocol, decorate your method class with [McpServerToolType], build the project, add a mcp.json under .vscode with the correct dotnet run command, then open GitHub Copilot Chat in Agent mode and click the Tools icon to see the available tools.

Key features of Build your MCP Server using C# SDK

• Demonstrates building an MCP server with the C# SDK.
• Provides three tools: echo, reverse, and length of a string.
• Easy integration with GitHub Copilot Chat (Agent mode).
• Uses official Microsoft NuGet packages for MCP.
• Fully open‑source sample for learning purposes.

Use cases of Build your MCP Server using C# SDK

• Learning how to create a custom MCP server in .NET.
• Testing MCP tool integration with GitHub Copilot.
• Prototyping simple string‑manipulation tools for AI assistants.
• Understanding the C# SDK decorator pattern ([McpServerToolType]).

FAQ from Build your MCP Server using C# SDK

What is the official C# SDK for MCP?

The official C# SDK is a library co‑created by Microsoft and Anthropic, announced on the MSFT blog. It provides the ModelContextProtocol NuGet package to build MCP servers in .NET.

What runtime dependencies are required?

You need .NET and the NuGet packages Microsoft.Extensions.Hosting and ModelContextProtocol.

What tools does the server expose?

Three tools: echo (returns the input unchanged), reverse (reverses the input string), and length (returns the character count of the input).

How do I run the server with GitHub Copilot?

Add an mcp.json file in the .vscode folder with a server entry pointing to dotnet run in the project directory, then restart VS Code and open Copilot Chat in Agent mode.

Does this server support authentication or transport configuration?

The README does not mention any authentication or transport settings. It relies on the standard MCP transport (stdin/stdout) used by the VS Code/Copilot integration.