Fix McpServerResource registration (#411)

- Add missing filling of ResourceCollection in McpServerOptionsSetup
- Remove AIFunctionMcpServerXx.ToString overrides; for resources, it was changing behavior undesirably, and for the others it was duplicate code.
- Fix notification method used for resource list changes.
- Fix type in WithResources parameter name.

Author: stephentoub

src/ModelContextProtocol/Configuration/McpServerBuilderExtensions.cs

@@ -334,16 +334,16 @@ where t.GetCustomAttribute<McpServerPromptTypeAttribute>() is not null
 
     /// <summary>Adds <see cref="McpServerResource"/> instances to the service collection backing <paramref name="builder"/>.</summary>
     /// <param name="builder">The builder instance.</param>
-    /// <param name="resourcetemplates">The <see cref="McpServerResource"/> instances to add to the server.</param>
+    /// <param name="resourceTemplates">The <see cref="McpServerResource"/> instances to add to the server.</param>
     /// <returns>The builder provided in <paramref name="builder"/>.</returns>
     /// <exception cref="ArgumentNullException"><paramref name="builder"/> is <see langword="null"/>.</exception>
-    /// <exception cref="ArgumentNullException"><paramref name="resourcetemplates"/> is <see langword="null"/>.</exception>
-    public static IMcpServerBuilder WithResources(this IMcpServerBuilder builder, IEnumerable<McpServerResource> resourcetemplates)
+    /// <exception cref="ArgumentNullException"><paramref name="resourceTemplates"/> is <see langword="null"/>.</exception>
+    public static IMcpServerBuilder WithResources(this IMcpServerBuilder builder, IEnumerable<McpServerResource> resourceTemplates)
     {
         Throw.IfNull(builder);
-        Throw.IfNull(resourcetemplates);
+        Throw.IfNull(resourceTemplates);
 
-        foreach (var resourceTemplate in resourcetemplates)
+        foreach (var resourceTemplate in resourceTemplates)
         {
             if (resourceTemplate is not null)
             {
@@ -409,7 +409,7 @@ public static IMcpServerBuilder WithResources(this IMcpServerBuilder builder, IE
     /// of the containing class will be constructed for each invocation of the resource.
     /// </para>
     /// <para>
-    /// Resource templates registered through this method can be discovered by clients using the <c>list_resourcetemplates</c> request
+    /// Resource templates registered through this method can be discovered by clients using the <c>list_resourceTemplates</c> request
     /// and invoked using the <c>read_resource</c> request.
     /// </para>
     /// <para>

src/ModelContextProtocol/Configuration/McpServerOptionsSetup.cs

@@ -10,10 +10,12 @@ namespace Microsoft.Extensions.DependencyInjection;
 /// <param name="serverHandlers">The server handlers configuration options.</param>
 /// <param name="serverTools">Tools individually registered.</param>
 /// <param name="serverPrompts">Prompts individually registered.</param>
+/// <param name="serverResources">Resources individually registered.</param>
 internal sealed class McpServerOptionsSetup(
     IOptions<McpServerHandlers> serverHandlers,
     IEnumerable<McpServerTool> serverTools,
-    IEnumerable<McpServerPrompt> serverPrompts) : IConfigureOptions<McpServerOptions>
+    IEnumerable<McpServerPrompt> serverPrompts,
+    IEnumerable<McpServerResource> serverResources) : IConfigureOptions<McpServerOptions>
 {
     /// <summary>
     /// Configures the given McpServerOptions instance by setting server information
@@ -58,6 +60,23 @@ public void Configure(McpServerOptions options)
             options.Capabilities.Prompts.PromptCollection = promptCollection;
         }
 
+        // Collect all of the provided resources into a resources collection. If the options already has
+        // a collection, add to it, otherwise create a new one. We want to maintain the identity
+        // of an existing collection in case someone has provided their own derived type, wants
+        // change notifications, etc.
+        McpServerPrimitiveCollection<McpServerResource> resourceCollection = options.Capabilities?.Resources?.ResourceCollection ?? [];
+        foreach (var resource in serverResources)
+        {
+            resourceCollection.TryAdd(resource);
+        }
+
+        if (!resourceCollection.IsEmpty)
+        {
+            options.Capabilities ??= new();
+            options.Capabilities.Resources ??= new();
+            options.Capabilities.Resources.ResourceCollection = resourceCollection;
+        }
+
         // Apply custom server handlers.
         serverHandlers.Value.OverwriteWithSetHandlers(options);
     }

src/ModelContextProtocol/Server/AIFunctionMcpServerPrompt.cs

@@ -216,9 +216,6 @@ private AIFunctionMcpServerPrompt(AIFunction function, Prompt prompt)
         ProtocolPrompt = prompt;
     }
 
-    /// <inheritdoc />
-    public override string ToString() => AIFunction.ToString();
-
     /// <inheritdoc />
     public override Prompt ProtocolPrompt { get; }
 

src/ModelContextProtocol/Server/AIFunctionMcpServerResource.cs

@@ -331,9 +331,6 @@ private AIFunctionMcpServerResource(AIFunction function, ResourceTemplate resour
         }
     }
 
-    /// <inheritdoc />
-    public override string ToString() => AIFunction.ToString();
-
     /// <inheritdoc />
     public override ResourceTemplate ProtocolResourceTemplate { get; }
 

src/ModelContextProtocol/Server/AIFunctionMcpServerTool.cs

@@ -247,9 +247,6 @@ private AIFunctionMcpServerTool(AIFunction function, Tool tool)
         ProtocolTool = tool;
     }
 
-    /// <inheritdoc />
-    public override string ToString() => AIFunction.ToString();
-
     /// <inheritdoc />
     public override Tool ProtocolTool { get; }
 

src/ModelContextProtocol/Server/McpServer.cs

@@ -81,26 +81,19 @@ public McpServer(ITransport transport, McpServerOptions options, ILoggerFactory?
         // Now that everything has been configured, subscribe to any necessary notifications.
         if (transport is not StreamableHttpServerTransport streamableHttpTransport || streamableHttpTransport.Stateless is false)
         {
-            if (ServerOptions.Capabilities?.Tools?.ToolCollection is { } tools)
-            {
-                EventHandler changed = (sender, e) => _ = this.SendNotificationAsync(NotificationMethods.ToolListChangedNotification);
-                tools.Changed += changed;
-                _disposables.Add(() => tools.Changed -= changed);
-            }
+            Register(ServerOptions.Capabilities?.Tools?.ToolCollection, NotificationMethods.ToolListChangedNotification);
+            Register(ServerOptions.Capabilities?.Prompts?.PromptCollection, NotificationMethods.PromptListChangedNotification);
+            Register(ServerOptions.Capabilities?.Resources?.ResourceCollection, NotificationMethods.ResourceListChangedNotification);
 
-            if (ServerOptions.Capabilities?.Prompts?.PromptCollection is { } prompts)
+            void Register<TPrimitive>(McpServerPrimitiveCollection<TPrimitive>? collection, string notificationMethod)
+                where TPrimitive : IMcpServerPrimitive
             {
-                EventHandler changed = (sender, e) => _ = this.SendNotificationAsync(NotificationMethods.PromptListChangedNotification);
-                prompts.Changed += changed;
-                _disposables.Add(() => prompts.Changed -= changed);
-            }
-
-            var resources = ServerOptions.Capabilities?.Resources?.ResourceCollection;
-            if (resources is not null)
-            {
-                EventHandler changed = (sender, e) => _ = this.SendNotificationAsync(NotificationMethods.PromptListChangedNotification);
-                resources.Changed += changed;
-                _disposables.Add(() => resources.Changed -= changed);
+                if (collection is not null)
+                {
+                    EventHandler changed = (sender, e) => _ = this.SendNotificationAsync(notificationMethod);
+                    collection.Changed += changed;
+                    _disposables.Add(() => collection.Changed -= changed);
+                }
             }
         }