✅Update AspNetCore sample to showcase ToolFilter

Author: jb.muscat

samples/AspNetCoreSseServer/Attributes/LimitCalls.cs

@@ -0,0 +1,31 @@
+using ModelContextProtocol.Core;
+using ModelContextProtocol.Protocol;
+using ModelContextProtocol.Server;
+
+namespace AspNetCoreSseServer.Attributes;
+
+public class LimitCalls(int maxCalls, int order = 0) : ToolFilter(order)
+{
+    private int _callCount;
+
+    public override ValueTask<CallToolResult>? OnToolCalling(Tool tool, RequestContext<CallToolRequestParams> context)
+    {
+        _callCount++;
+        Console.Out.WriteLine($"Tool: {tool.Name} called {_callCount} time(s)");
+
+        if (_callCount <= maxCalls)
+            return null; //do nothing
+
+        return new ValueTask<CallToolResult>(new CallToolResult()
+        {
+            Content = [new TextContentBlock { Text = $"This tool can only be called {maxCalls} time(s)" }]
+        });
+    }
+
+    public override bool OnToolListed(Tool tool, RequestContext<ListToolsRequestParams> context)
+    {
+        var configuration = context.Services?.GetService<IConfiguration>();
+        var hide = configuration?["hide-tools-above-limit"] == "True";
+        return hide && _callCount <= maxCalls;
+    }
+}

samples/AspNetCoreSseServer/Tools/EchoTool.cs

@@ -1,12 +1,14 @@
 using ModelContextProtocol.Server;
 using System.ComponentModel;
+using AspNetCoreSseServer.Attributes;
 
 namespace TestServerWithHosting.Tools;
 
 [McpServerToolType]
 public sealed class EchoTool
 {
     [McpServerTool, Description("Echoes the input back to the client.")]
+    [LimitCalls(maxCalls: 10)]
     public static string Echo(string message)
     {
         return "hello " + message;

samples/AspNetCoreSseServer/appsettings.json

@@ -5,5 +5,6 @@
       "Microsoft.AspNetCore": "Warning"
     }
   },
-  "AllowedHosts": "*"
+  "AllowedHosts": "*",
+  "hide-tools-above-limit": true
 }