Add WithTools/Prompts overloads that accept McpServerTool/Prompts (#319)

To avoid folks needing to know how you should be registering tool instances into DI.

Author: stephentoub

src/ModelContextProtocol/Configuration/McpServerBuilderExtensions.cs

@@ -57,7 +57,29 @@ public static partial class McpServerBuilderExtensions
 
     /// <summary>Adds <see cref="McpServerTool"/> instances to the service collection backing <paramref name="builder"/>.</summary>
     /// <param name="builder">The builder instance.</param>
-    /// <param name="toolTypes">Types with marked methods to add as tools to the server.</param>
+    /// <param name="tools">The <see cref="McpServerTool"/> 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="tools"/> is <see langword="null"/>.</exception>
+    public static IMcpServerBuilder WithTools(this IMcpServerBuilder builder, IEnumerable<McpServerTool> tools)
+    {
+        Throw.IfNull(builder);
+        Throw.IfNull(tools);
+
+        foreach (var tool in tools)
+        {
+            if (tool is not null)
+            {
+                builder.Services.AddSingleton(tool);
+            }
+        }
+
+        return builder;
+    }
+
+    /// <summary>Adds <see cref="McpServerTool"/> instances to the service collection backing <paramref name="builder"/>.</summary>
+    /// <param name="builder">The builder instance.</param>
+    /// <param name="toolTypes">Types with <see cref="McpServerToolAttribute"/>-attributed methods to add as tools to the server.</param>
     /// <param name="serializerOptions">The serializer options governing tool parameter marshalling.</param>
     /// <returns>The builder provided in <paramref name="builder"/>.</returns>
     /// <exception cref="ArgumentNullException"><paramref name="builder"/> is <see langword="null"/>.</exception>
@@ -173,6 +195,28 @@ where t.GetCustomAttribute<McpServerToolTypeAttribute>() is not null
         return builder;
     }
 
+    /// <summary>Adds <see cref="McpServerPrompt"/> instances to the service collection backing <paramref name="builder"/>.</summary>
+    /// <param name="builder">The builder instance.</param>
+    /// <param name="prompts">The <see cref="McpServerPrompt"/> 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="prompts"/> is <see langword="null"/>.</exception>
+    public static IMcpServerBuilder WithPrompts(this IMcpServerBuilder builder, IEnumerable<McpServerPrompt> prompts)
+    {
+        Throw.IfNull(builder);
+        Throw.IfNull(prompts);
+
+        foreach (var prompt in prompts)
+        {
+            if (prompt is not null)
+            {
+                builder.Services.AddSingleton(prompt);
+            }
+        }
+
+        return builder;
+    }
+
     /// <summary>Adds <see cref="McpServerPrompt"/> instances to the service collection backing <paramref name="builder"/>.</summary>
     /// <param name="builder">The builder instance.</param>
     /// <param name="promptTypes">Types with marked methods to add as prompts to the server.</param>

tests/ModelContextProtocol.Tests/Client/McpClientExtensionsTests.cs

@@ -25,10 +25,10 @@ protected override void ConfigureServices(ServiceCollection services, IMcpServer
         for (int f = 0; f < 10; f++)
         {
             string name = $"Method{f}";
-            services.AddSingleton(McpServerTool.Create((int i) => $"{name} Result {i}", new() { Name = name }));
+            mcpServerBuilder.WithTools([McpServerTool.Create((int i) => $"{name} Result {i}", new() { Name = name })]);
         }
-        services.AddSingleton(McpServerTool.Create([McpServerTool(Destructive = false, OpenWorld = true)] (string i) => $"{i} Result", new() { Name = "ValuesSetViaAttr" }));
-        services.AddSingleton(McpServerTool.Create([McpServerTool(Destructive = false, OpenWorld = true)] (string i) => $"{i} Result", new() { Name = "ValuesSetViaOptions", Destructive = true, OpenWorld = false, ReadOnly = true }));
+        mcpServerBuilder.WithTools([McpServerTool.Create([McpServerTool(Destructive = false, OpenWorld = true)] (string i) => $"{i} Result", new() { Name = "ValuesSetViaAttr" })]);
+        mcpServerBuilder.WithTools([McpServerTool.Create([McpServerTool(Destructive = false, OpenWorld = true)] (string i) => $"{i} Result", new() { Name = "ValuesSetViaOptions", Destructive = true, OpenWorld = false, ReadOnly = true })]);
     }
 
     [Theory]

tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsPromptsTests.cs

@@ -202,6 +202,7 @@ public void WithPrompts_InvalidArgs_Throws()
     {
         IMcpServerBuilder builder = new ServiceCollection().AddMcpServer();
 
+        Assert.Throws<ArgumentNullException>("prompts", () => builder.WithPrompts((IEnumerable<McpServerPrompt>)null!));
         Assert.Throws<ArgumentNullException>("promptTypes", () => builder.WithPrompts((IEnumerable<Type>)null!));
 
         IMcpServerBuilder nullBuilder = null!;
@@ -215,6 +216,7 @@ public void Empty_Enumerables_Is_Allowed()
     {
         IMcpServerBuilder builder = new ServiceCollection().AddMcpServer();
 
+        builder.WithPrompts(prompts: []); // no exception
         builder.WithPrompts(promptTypes: []); // no exception
         builder.WithPrompts<object>(); // no exception even though no prompts exposed
         builder.WithPromptsFromAssembly(typeof(AIFunction).Assembly); // no exception even though no prompts exposed
@@ -236,13 +238,15 @@ public void Register_Prompts_From_Multiple_Sources()
         ServiceCollection sc = new();
         sc.AddMcpServer()
             .WithPrompts<SimplePrompts>()
-            .WithPrompts<MorePrompts>(JsonContext4.Default.Options);
+            .WithPrompts<MorePrompts>(JsonContext4.Default.Options)
+            .WithPrompts([McpServerPrompt.Create(() => "42", new() { Name = "Returns42" })]);
         IServiceProvider services = sc.BuildServiceProvider();
 
         Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == nameof(SimplePrompts.ReturnsChatMessages));
         Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == nameof(SimplePrompts.ThrowsException));
         Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == nameof(SimplePrompts.ReturnsString));
         Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == nameof(MorePrompts.AnotherPrompt));
+        Assert.Contains(services.GetServices<McpServerPrompt>(), t => t.ProtocolPrompt.Name == "Returns42");
     }
 
     [McpServerPromptType]

tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsToolsTests.cs

@@ -408,6 +408,7 @@ public void WithTools_InvalidArgs_Throws()
     {
         IMcpServerBuilder builder = new ServiceCollection().AddMcpServer();
 
+        Assert.Throws<ArgumentNullException>("tools", () => builder.WithTools((IEnumerable<McpServerTool>)null!));
         Assert.Throws<ArgumentNullException>("toolTypes", () => builder.WithTools((IEnumerable<Type>)null!));
 
         IMcpServerBuilder nullBuilder = null!;
@@ -421,6 +422,7 @@ public void Empty_Enumerables_Is_Allowed()
     {
         IMcpServerBuilder builder = new ServiceCollection().AddMcpServer();
 
+        builder.WithTools(tools: []); // no exception
         builder.WithTools(toolTypes: []); // no exception
         builder.WithTools<object>(); // no exception even though no tools exposed
         builder.WithToolsFromAssembly(typeof(AIFunction).Assembly); // no exception even though no tools exposed
@@ -539,14 +541,16 @@ public void Register_Tools_From_Multiple_Sources()
         sc.AddMcpServer()
             .WithTools<EchoTool>(serializerOptions: BuilderToolsJsonContext.Default.Options)
             .WithTools<AnotherToolType>(serializerOptions: BuilderToolsJsonContext.Default.Options)
-            .WithTools([typeof(ToolTypeWithNoAttribute)], BuilderToolsJsonContext.Default.Options);
+            .WithTools([typeof(ToolTypeWithNoAttribute)], BuilderToolsJsonContext.Default.Options)
+            .WithTools([McpServerTool.Create(() => "42", new() { Name = "Returns42" })]);
         IServiceProvider services = sc.BuildServiceProvider();
 
         Assert.Contains(services.GetServices<McpServerTool>(), t => t.ProtocolTool.Name == "double_echo");
         Assert.Contains(services.GetServices<McpServerTool>(), t => t.ProtocolTool.Name == "DifferentName");
         Assert.Contains(services.GetServices<McpServerTool>(), t => t.ProtocolTool.Name == "MethodB");
         Assert.Contains(services.GetServices<McpServerTool>(), t => t.ProtocolTool.Name == "MethodC");
         Assert.Contains(services.GetServices<McpServerTool>(), t => t.ProtocolTool.Name == "MethodD");
+        Assert.Contains(services.GetServices<McpServerTool>(), t => t.ProtocolTool.Name == "Returns42");
     }
 
     [Fact]