Nall.ModelContextProtocol.Inspector.Aspire.Hosting 0.4.0

Model Context Protocol .NET Template

This repository contains a template for creating a Model Context Protocol (MCP) application in .NET. It provides a basic structure and example code to help you get started with building your own MCP-enabled applications.

Package	Version	Description
Nall.ModelContextProtocol.Template		Templates
Nall.ModelContextProtocol.Inspector.Aspire.Hosting		Aspire Hosting Integration

Getting Started

Install:

dotnet new install Nall.ModelContextProtocol.Template

Verify installation:

dotnet new list mcp
# These templates matched your input: 'mcp'

# Template Name      Short Name         Language  Tags
# -----------------  -----------------  --------  -------------
# MCP Server         mcp-server         [C#]      dotnet/ai/mcp
# MCP Server SSE     mcp-server-sse     [C#]      dotnet/ai/mcp
# MCP Server Hybrid  mcp-server-hybrid  [C#]      dotnet/ai/mcp

[!INFO] Based on my experience, it is convenient to be able to switch between mode, so I recommend using mcp-server-hybrid template. It allows you to run the server in both Stdio and SSE modes.

Verify output:

dotnet new mcp-server -o MyAwesomeMCPServer -n MyAwesomeMCPServer --dry-run
# File actions would have been taken:
#   Create: MyAwesomeMCPServer\.vscode\launch.json
#   Create: MyAwesomeMCPServer\MyAwesomeMCPServer.csproj
#   Create: MyAwesomeMCPServer\Program.cs
#   Create: MyAwesomeMCPServer\Properties\launchSettings.json
#   Create: MyAwesomeMCPServer\README.md
#   Create: MyAwesomeMCPServer\appsettings.Development.json
#   Create: MyAwesomeMCPServer\appsettings.json

Create from template:

dotnet new mcp-server -o MyAwesomeMCPServer -n MyAwesomeMCPServer

Here is a content of Program.cs:

using Microsoft.Extensions.Hosting;

var builder = Host.CreateApplicationBuilder(args);
builder.Services
    .AddMcpServer()
    .WithStdioServerTransport()
    .WithToolsFromAssembly();

await builder.Build().RunAsync();

[McpServerToolType]
public static class EchoTool
{
    [McpServerTool, Description("Echoes the message back to the client.")]
    public static string Echo(string message) => $"hello {message}";
}

It is a simple echo server that listens for incoming messages and responds with a greeting. You can add more tools by creating additional methods with the [McpServerTool] attribute. The WithToolsFromAssembly() method automatically registers all tools in the assembly.

Run Locally

Build from the project directory:

dotnet build -o Artefacts -c Release

Run the inspector:

npx @modelcontextprotocol/inspector -e DOTNET_ENVIRONMENT=Production dotnet "$(PWD)/Artefacts/MyAwesomeMCPServer.dll"

Open inspector in your browser and test the server:

<p align="center"> <img src="assets/inspector-demo.png" alt="Inspector Demo" /> </p>

Distribute as .NET Tool

Pack from the project directory:

dotnet pack -o Artefacts -c Release

Install the tool globally:

dotnet tool install --global --add-source ./Artefacts MyAwesomeMCPServer

Now, after you installed this tool globally, you can run it from anywhere on your system. The tool will be available as MyAwesomeMCPServer (or myawesomemcpserver) in your terminal.

💡 You can also create local tool manifest and install MCPs as tools locally.

Run the inspector:

npx @modelcontextprotocol/inspector -e DOTNET_ENVIRONMENT=Production myawesomemcpserver

Run with Aspire

In Stdio mode

In AppHost/Program.cs:

var builder = DistributedApplication.CreateBuilder(args);

builder.AddMCPInspector().WithStdio<Projects.MCPServer>();

builder.Build().Run();

In SSE mode

In AppHost/Program.cs:

var builder = DistributedApplication.CreateBuilder(args);

var mcp = builder.AddProject<Projects.MCPServerSSE>("server");
builder.AddMCPInspector().WithSSE(mcp);

builder.Build().Run();

Reference

• https://learn.microsoft.com/en-us/dotnet/core/tools/custom-templates
• https://learn.microsoft.com/en-us/dotnet/core/tools/global-tools