jeff / basic_dotnet_mcp_server.cs

/* dotnet add package ModelContextProtocol --prerelease dotnet add package ModelContextProtocol.AspNetCore --prerelease dotnet add package Microsoft.Extensions.Hosting */ using ModelContextProtocol.Server; using System.ComponentModel; var builder = WebApplication.CreateBuilder(args); builder.Services.AddMcpServer() .WithHttpTransport() .WithToolsFromAssembly(); var app = builder.Build(); // validate Authorization header on incoming requests app.Use(async (context, next) => { if (!context.Request.Headers.TryGetValue("Authorization", out var auth) || auth != "Bearer hello-world") { context.Response.StatusCode = StatusCodes.Status401Unauthorized; return; } await next(); }); app.MapMcp(); app.Run("http://localhost:3001"); [McpServerToolType] public static class EchoTool { [McpServerTool, Description("Echoes the message back to the client.")] public static string Echo(string message) => $"Yo! You said '{message}'"; } // Add a strongly-typed response class for weather public record WeatherResponse(string City, int Temperature, int Humidity, string Condition); [McpServerToolType] public static class WeatherTool { [McpServerTool, Description("Returns weather data as a typed object; framework will serialize to JSON.")] public static WeatherResponse GetWeather(string? city) { string cityName = city ?? string.Empty; int temperature = cityName.Length; int humidity = temperature * 5; var conditions = new[] { "Sunny", "Cloudy", "Rainy", "Windy" }; string condition = conditions[temperature % conditions.Length]; return new WeatherResponse(cityName, temperature, humidity, condition); } }