MCP Server

This README was created using the C# MCP server project template. It demonstrates how you can easily create an MCP server using C# and publish it as a NuGet package.

The MCP server is built as a self-contained application and does not require the .NET runtime to be installed on the target machine. However, since it is self-contained, it must be built for each target platform separately. By default, the template is configured to build for:

• win-x64
• win-arm64
• osx-arm64
• linux-x64
• linux-arm64
• linux-musl-x64

If your users require more platforms to be supported, update the list of runtime identifiers in the project's <RuntimeIdentifiers /> element.

See aka.ms/nuget/mcp/guide for the full guide.

Please note that this template is currently in an early preview stage. If you have feedback, please take a brief survey.

Checklist before publishing to NuGet.org

• Test the MCP server locally using the steps below.
• Update the package metadata in the .csproj file, in particular the <PackageId>.
• Update .mcp/server.json to declare your MCP server's inputs.
  • See configuring inputs for more details.
• Pack the project using dotnet pack.

The bin/Release directory will contain the package file (.nupkg), which can be published to NuGet.org.

Developing locally

To test this MCP server from source code (locally) without using a built MCP server package, you can configure your IDE to run the project directly using dotnet run.

{
  "servers": {
    "MyMcpServer": {
      "type": "stdio",
      "command": "dotnet",
      "args": [
        "run",
        "--project",
        "<PATH TO PROJECT DIRECTORY>"
      ]
    }
  }
}

Refer to the VS Code or Visual Studio documentation for more information on configuring and using MCP servers:

• Use MCP servers in VS Code (Preview)
• Use MCP servers in Visual Studio (Preview)

Testing the MCP Server

Once configured, you can ask Copilot Chat for a random number, for example, Give me 3 random numbers. It should prompt you to use the get_random_number tool on the MyMcpServer MCP server and show you the results.

Publishing to NuGet.org

1. Run dotnet pack -c Release to create the NuGet package
2. Publish to NuGet.org with dotnet nuget push bin/Release/*.nupkg --api-key <your-api-key> --source https://api.nuget.org/v3/index.json

Using the MCP Server from NuGet.org

Once the MCP server package is published to NuGet.org, you can configure it in your preferred IDE. Both VS Code and Visual Studio use the dnx command to download and install the MCP server package from NuGet.org.

• VS Code: Create a <WORKSPACE DIRECTORY>/.vscode/mcp.json file
• Visual Studio: Create a <SOLUTION DIRECTORY>\.mcp.json file

For both VS Code and Visual Studio, the configuration file uses the following server definition:

{
  "servers": {
    "MyMcpServer": {
      "type": "stdio",
      "command": "dnx",
      "args": [
        "<your package ID here>",
        "--version",
        "<your package version here>",
        "--yes"
      ]
    }
  }
}

More information

.NET MCP servers use the ModelContextProtocol C# SDK. For more information about MCP:

• Official Documentation
• Protocol Specification
• GitHub Organization
• MCP C# SDK