Add extension to register a tool individually

This does away with the need to have a type for the individual tools at all.

Author: kzu

src/MCPDemo/Program.cs

@@ -1,58 +1,47 @@
-using ModelContextProtocol.Server;
-using SixLabors.ImageSharp;
+using SixLabors.ImageSharp;
 using SixLabors.ImageSharp.PixelFormats;
 
 var builder = App.CreateBuilder(args);
 builder.Services.AddHttpClient();
-builder.Logging.AddConsole(consoleLogOptions =>
-{
-    // Configure all logs to go to stderr
-    consoleLogOptions.LogToStandardErrorThreshold = LogLevel.Trace;
-});
 
 builder.Services
     .AddMcpServer()
     .WithStdioServerTransport()
-    .WithToolsFromAssembly();
-
-await builder.Build().RunAsync();
-
-[McpServerToolType]
-public class LaTeX(IHttpClientFactory httpFactory)
-{
-    [McpServerTool, Description("Converts LaTeX equations into markdown-formatted images for display inline.")]
-    public async Task<string> LatexMarkdown(
+    .WithTool(
+        [Description("Converts LaTeX equations into markdown-formatted images for display inline.")] async
+        (IHttpClientFactory httpFactory,
         [Description("The LaTeX equation to render.")] string latex,
-        [Description("Use dark mode by inverting the colors in the output.")] bool darkMode)
-    {
-        var colors = darkMode ? @"\bg{black}\fg{white}" : @"\bg{white}\fg{black}";
-        var query = WebUtility.UrlEncode(@"\small\dpi{300}" + colors + latex);
-        var url = $"https://latex.codecogs.com/png.image?{query}";
-        using var client = httpFactory.CreateClient();
-        using var response = await client.GetAsync(url);
-
-        if (response.IsSuccessStatusCode)
+        [Description("Use dark mode by inverting the colors in the output.")] bool darkMode) =>
         {
-            using var image = Image.Load<Rgba32>(await response.Content.ReadAsStreamAsync());
-            using var ms = new MemoryStream();
-            image.SaveAsPng(ms);
-            var base64 = Convert.ToBase64String(ms.ToArray());
-            return
-                $"""
+            var colors = darkMode ? @"\bg{black}\fg{white}" : @"\bg{white}\fg{black}";
+            var query = WebUtility.UrlEncode(@"\small\dpi{300}" + colors + latex);
+            var url = $"https://latex.codecogs.com/png.image?{query}";
+            using var client = httpFactory.CreateClient();
+            using var response = await client.GetAsync(url);
+
+            if (response.IsSuccessStatusCode)
+            {
+                using var image = Image.Load<Rgba32>(await response.Content.ReadAsStreamAsync());
+                using var ms = new MemoryStream();
+                image.SaveAsPng(ms);
+                var base64 = Convert.ToBase64String(ms.ToArray());
+                return
+                    $"""
                 ![{latex}](
                 data:image/png;base64,{base64}
                 )
                 """;
-        }
-        else
-        {
-            return
-                $"""
+            }
+            else
+            {
+                return
+                    $"""
                 ```latex
                 {latex}
                 ```
                 > {response.ReasonPhrase}
                 """;
-        }
-    }
-}
+            }
+        });
+
+await builder.Build().RunAsync();

src/Smith/McpExtensions.cs

@@ -0,0 +1,25 @@
+using System.Text.Json;
+using Microsoft.Extensions.DependencyInjection;
+using ModelContextProtocol.Server;
+
+namespace Smith;
+
+/// <summary>
+/// Usability extensions for working with MCP.
+/// </summary>
+public static class McpExtensions
+{
+    extension(IMcpServerBuilder builder)
+    {
+        /// <summary>
+        /// Registers a specific method as a server tool.
+        /// </summary>
+        public IMcpServerBuilder WithTool(Delegate tool, JsonSerializerOptions? options = null)
+        {
+            builder.Services.AddSingleton(services
+                => McpServerTool.Create(tool, new() { Services = services, SerializerOptions = options }));
+
+            return builder;
+        }
+    }
+}