Fix some issues with Native AOT

- An anonymous type was being used in McpClient for the initialize result message. Switched to use the type for that purpose that already existed.
- A bunch of the request params / result types were not in the source context or referenced from types that were or from custom converters. Added all the request/result types to the context.
- Improved the warning message for WithTools.

Author: stephentoub

src/ModelContextProtocol/Client/McpClient.cs

@@ -6,7 +6,6 @@
 using ModelContextProtocol.Shared;
 using ModelContextProtocol.Utils.Json;
 using Microsoft.Extensions.Logging;
-using Microsoft.Extensions.Logging.Abstractions;
 using System.Text.Json;
 
 namespace ModelContextProtocol.Client;
@@ -126,11 +125,11 @@ private async Task InitializeAsync(CancellationToken cancellationToken)
                 new JsonRpcRequest
                 {
                     Method = "initialize",
-                    Params = new
+                    Params = new InitializeRequestParams()
                     {
-                        protocolVersion = _options.ProtocolVersion,
-                        capabilities = _options.Capabilities ?? new ClientCapabilities(),
-                        clientInfo = _options.ClientInfo
+                        ProtocolVersion = _options.ProtocolVersion,
+                        Capabilities = _options.Capabilities ?? new ClientCapabilities(),
+                        ClientInfo = _options.ClientInfo
                     }
                 },
                 initializationCts.Token).ConfigureAwait(false);

src/ModelContextProtocol/Configuration/McpServerBuilderExtensions.Tools.cs

@@ -12,7 +12,9 @@ namespace ModelContextProtocol;
 /// </summary>
 public static partial class McpServerBuilderExtensions
 {
-    private const string RequiresUnreferencedCodeMessage = "This method requires dynamic lookup of method metadata and might not work in Native AOT.";
+    private const string WithToolsRequiresUnreferencedCodeMessage = 
+        $"The non-generic {nameof(WithTools)} and {nameof(WithToolsFromAssembly)} methods require dynamic lookup of method metadata" +
+        $"and may not work in Native AOT. Use the generic {nameof(WithTools)} method instead.";
 
     /// <summary>Adds <see cref="McpServerTool"/> instances to the service collection backing <paramref name="builder"/>.</summary>
     /// <typeparam name="TTool">The tool type.</typeparam>
@@ -59,7 +61,7 @@ public static partial class McpServerBuilderExtensions
     /// types, where the methods are attributed as <see cref="McpServerToolAttribute"/>, and adds an <see cref="McpServerTool"/>
     /// instance for each. For instance methods, an instance will be constructed for each invocation of the tool.
     /// </remarks>
-    [RequiresUnreferencedCode(RequiresUnreferencedCodeMessage)]
+    [RequiresUnreferencedCode(WithToolsRequiresUnreferencedCodeMessage)]
     public static IMcpServerBuilder WithTools(this IMcpServerBuilder builder, params IEnumerable<Type> toolTypes)
     {
         Throw.IfNull(builder);
@@ -95,7 +97,7 @@ public static IMcpServerBuilder WithTools(this IMcpServerBuilder builder, params
     /// <param name="builder">The builder instance.</param>
     /// <param name="toolAssembly">The assembly to load the types from. Null to get the current assembly</param>
     /// <exception cref="ArgumentNullException"><paramref name="builder"/> is <see langword="null"/>.</exception>
-    [RequiresUnreferencedCode(RequiresUnreferencedCodeMessage)]
+    [RequiresUnreferencedCode(WithToolsRequiresUnreferencedCodeMessage)]
     public static IMcpServerBuilder WithToolsFromAssembly(this IMcpServerBuilder builder, Assembly? toolAssembly = null)
     {
         Throw.IfNull(builder);

src/ModelContextProtocol/Protocol/Messages/JsonRpcMessage.cs renamed to src/ModelContextProtocol/Protocol/Messages/JsonRpcRequest.cs

@@ -1,5 +1,4 @@
 using Microsoft.Extensions.Logging;
-using Microsoft.Extensions.Logging.Abstractions;
 using ModelContextProtocol.Logging;
 using ModelContextProtocol.Protocol.Messages;
 using ModelContextProtocol.Protocol.Transport;

src/ModelContextProtocol/Server/McpServer.cs

@@ -105,21 +105,50 @@ internal static bool IsValidMcpToolSchema(JsonElement element)
         UseStringEnumConverter = true,
         DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
         NumberHandling = JsonNumberHandling.AllowReadingFromString)]
+
+    // JSON
     [JsonSerializable(typeof(JsonDocument))]
     [JsonSerializable(typeof(JsonElement))]
     [JsonSerializable(typeof(JsonNode))]
+    
+    // JSON-RPC
     [JsonSerializable(typeof(IJsonRpcMessage))]
     [JsonSerializable(typeof(JsonRpcRequest))]
     [JsonSerializable(typeof(JsonRpcNotification))]
     [JsonSerializable(typeof(JsonRpcResponse))]
     [JsonSerializable(typeof(JsonRpcError))]
-    [JsonSerializable(typeof(ServerCapabilities))]
-    [JsonSerializable(typeof(ClientCapabilities))]
-    [JsonSerializable(typeof(Implementation))]
+
+    // MCP Request Params / Results
+    [JsonSerializable(typeof(CallToolRequestParams))]
+    [JsonSerializable(typeof(CallToolResponse))]
+    [JsonSerializable(typeof(CompleteRequestParams))]
+    [JsonSerializable(typeof(CompleteResult))]
+    [JsonSerializable(typeof(CreateMessageRequestParams))]
     [JsonSerializable(typeof(CreateMessageResult))]
-    [JsonSerializable(typeof(ListRootsResult))]
+    [JsonSerializable(typeof(EmptyResult))]
+    [JsonSerializable(typeof(GetPromptRequestParams))]
+    [JsonSerializable(typeof(GetPromptResult))]
+    [JsonSerializable(typeof(InitializeRequestParams))]
     [JsonSerializable(typeof(InitializeResult))]
-    [JsonSerializable(typeof(CallToolResponse))]
+    [JsonSerializable(typeof(ListPromptsRequestParams))]
+    [JsonSerializable(typeof(ListPromptsResult))]
+    [JsonSerializable(typeof(ListResourcesRequestParams))]
+    [JsonSerializable(typeof(ListResourcesResult))]
+    [JsonSerializable(typeof(ListResourceTemplatesRequestParams))]
+    [JsonSerializable(typeof(ListResourceTemplatesResult))]
+    [JsonSerializable(typeof(ListRootsRequestParams))]
+    [JsonSerializable(typeof(ListRootsResult))]
+    [JsonSerializable(typeof(ListToolsRequestParams))]
+    [JsonSerializable(typeof(ListToolsResult))]
+    [JsonSerializable(typeof(LoggingMessageNotificationParams))]
+    [JsonSerializable(typeof(PingResult))]
+    [JsonSerializable(typeof(ReadResourceRequestParams))]
+    [JsonSerializable(typeof(ReadResourceResult))]
+    [JsonSerializable(typeof(ResourceUpdatedNotificationParams))]
+    [JsonSerializable(typeof(SetLevelRequestParams))]
+    [JsonSerializable(typeof(SubscribeRequestParams))]
+    [JsonSerializable(typeof(UnsubscribeFromResourceRequestParams))]
+    [JsonSerializable(typeof(UnsubscribeRequestParams))]
     internal sealed partial class JsonContext : JsonSerializerContext;
 
     private static JsonElement ParseJsonElement(ReadOnlySpan<byte> utf8Json)

src/ModelContextProtocol/Utils/Json/McpJsonUtilities.cs

@@ -1,5 +1,4 @@
-using Microsoft.Extensions.AI;
-using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection;
 using ModelContextProtocol.Protocol.Types;
 using ModelContextProtocol.Server;
 using Moq;

tests/ModelContextProtocol.Tests/Server/McpServerToolTests.cs

@@ -4,6 +4,7 @@
 using ModelContextProtocol.Protocol.Messages;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
+using ModelContextProtocol.Protocol.Types;
 
 namespace ModelContextProtocol.Tests.Utils;
 
@@ -288,19 +289,14 @@ private static async Task HandleInitializationRequest(HttpListenerResponse respo
         var jsonRpcResponse = new JsonRpcResponse()
         {
             Id = jsonRpcRequest.Id,
-            Result = new
+            Result = new InitializeResult()
             {
-                protocolVersion = "2024-11-05",
-                capabilities = new
+                ProtocolVersion = "2024-11-05",
+                Capabilities = new(),
+                ServerInfo = new()
                 {
-                    experimental = (object?)null,
-                    roots = (object?)null,
-                    sampling = (object?)null
-                },
-                serverInfo = new
-                {
-                    name = "ExampleServer",
-                    version = "1.0.0"
+                    Name = "ExampleServer",
+                    Version = "1.0.0"
                 }
             }
         };