Respect DI while creating target object

Author: dogukandemir

Directory.Packages.props

@@ -6,6 +6,11 @@
     <MicrosoftExtensionsAIVersion>9.7.1</MicrosoftExtensionsAIVersion>
   </PropertyGroup>
 
+  <!-- Product dependencies .NET Framework 4.7.2 -->
+  <ItemGroup Condition="'$(TargetFramework)' == 'net472'">
+    <PackageVersion Include="Microsoft.Extensions.Http" Version="8.0.1" />
+  </ItemGroup>
+
   <!-- Product dependencies netstandard -->
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageVersion Include="Microsoft.Bcl.Memory" Version="$(System9Version)" />
@@ -20,6 +25,7 @@
   <!-- Product dependencies LTS -->
   <ItemGroup Condition="'$(TargetFramework)' == 'net8.0'">
     <PackageVersion Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="8.0.15" />
+    <PackageVersion Include="Microsoft.Extensions.Http" Version="8.0.1" />
     <PackageVersion Include="Microsoft.Extensions.Hosting.Abstractions" Version="8.0.1" />
     <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.3" />
     <PackageVersion Include="System.IO.Pipelines" Version="8.0.0" />
@@ -29,6 +35,7 @@
   <ItemGroup Condition="'$(TargetFramework)' == 'net9.0'">
     <PackageVersion Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="$(System9Version)" />
     <PackageVersion Include="Microsoft.IdentityModel.Tokens" Version="8.9.0" />
+    <PackageVersion Include="Microsoft.Extensions.Http" Version="$(System9Version)" />
     <PackageVersion Include="Microsoft.Extensions.Hosting.Abstractions" Version="$(System9Version)" />
     <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="$(System9Version)" />
     <PackageVersion Include="System.IO.Pipelines" Version="$(System9Version)" />

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerPrompt.cs

@@ -76,8 +76,8 @@ private static AIFunctionFactoryOptions CreateAIFunctionFactoryOptions(
             ConfigureParameterBinding = pi =>
             {
                 if (RequestServiceProvider<GetPromptRequestParams>.IsAugmentedWith(pi.ParameterType) ||
-                    (options?.Services?.GetService<IServiceProviderIsService>() is { } ispis &&
-                     ispis.IsService(pi.ParameterType)))
+                    (options?.Services?.GetService<IServiceProviderIsService>() is { } serviceProviderIsService &&
+                     serviceProviderIsService.IsService(pi.ParameterType)))
                 {
                     return new()
                     {

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerResource.cs

@@ -83,8 +83,8 @@ private static AIFunctionFactoryOptions CreateAIFunctionFactoryOptions(
             ConfigureParameterBinding = pi =>
             {
                 if (RequestServiceProvider<ReadResourceRequestParams>.IsAugmentedWith(pi.ParameterType) ||
-                    (options?.Services?.GetService<IServiceProviderIsService>() is { } ispis &&
-                     ispis.IsService(pi.ParameterType)))
+                    (options?.Services?.GetService<IServiceProviderIsService>() is { } serviceProviderIsService &&
+                     serviceProviderIsService.IsService(pi.ParameterType)))
                 {
                     return new()
                     {

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerTool.cs

@@ -83,8 +83,8 @@ private static AIFunctionFactoryOptions CreateAIFunctionFactoryOptions(
             ConfigureParameterBinding = pi =>
             {
                 if (RequestServiceProvider<CallToolRequestParams>.IsAugmentedWith(pi.ParameterType) ||
-                    (options?.Services?.GetService<IServiceProviderIsService>() is { } ispis &&
-                     ispis.IsService(pi.ParameterType)))
+                    (options?.Services?.GetService<IServiceProviderIsService>() is { } serviceProviderIsService &&
+                     serviceProviderIsService.IsService(pi.ParameterType)))
                 {
                     return new()
                     {

src/ModelContextProtocol/McpServerBuilderExtensions.cs

@@ -783,8 +783,18 @@ private static void AddSingleSessionServerDependencies(IServiceCollection servic
     /// <summary>Creates an instance of the target object.</summary>
     private static object CreateTarget(
         IServiceProvider? services,
-        [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type) =>
-        services is not null ? ActivatorUtilities.CreateInstance(services, type) :
-        Activator.CreateInstance(type)!;
+        [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+    {
+        if (services is null)
+        {
+            return Activator.CreateInstance(type)!;
+        }
+
+        var isService = services.GetService<IServiceProviderIsService>()?.IsService(type) == true;
+
+        return isService
+            ? services.GetRequiredService(type) 
+            : ActivatorUtilities.CreateInstance(services, type);
+    }
     #endregion
 }

tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsCreateTargetHelperTests.cs

@@ -0,0 +1,58 @@
+using Microsoft.Extensions.DependencyInjection;
+using ModelContextProtocol.Client;
+using ModelContextProtocol.Protocol;
+using ModelContextProtocol.Server;
+using System.ComponentModel;
+
+namespace ModelContextProtocol.Tests.Configuration;
+
+public class McpServerBuilderExtensionsCreateTargetHelperTests(ITestOutputHelper testOutputHelper) 
+    : ClientServerTestBase(testOutputHelper)
+{
+    private const string ToolName = "Pets Service";
+    private const string BaseAddress = "https://localhost:7387/pets";
+
+    protected override void ConfigureServices(ServiceCollection services, IMcpServerBuilder mcpServerBuilder)
+    {
+        mcpServerBuilder.WithTools<PetsService>();
+
+        services.AddHttpClient<PetsService>(client =>
+        {
+            client.BaseAddress = new Uri(BaseAddress);
+        });
+    }
+
+    /// <summary>
+    /// Verifies that a typed HttpClient registered in DI is correctly injected into a server tool
+    /// and used by the tool implementation. This test covers the scenario described in
+    /// https://github.com/modelcontextprotocol/csharp-sdk/issues/685.
+    /// </summary>
+    [Fact]
+    public async Task Typed_HttpClient_Is_Used_By_Tool()
+    {
+        // Arrange
+        await using var client = await CreateMcpClientForServer();
+
+        // Act
+        var result = await client.CallToolAsync(ToolName, cancellationToken: TestContext.Current.CancellationToken);
+
+        // Assert
+        Assert.NotNull(result.Content);
+        Assert.NotEmpty(result.Content);
+
+        var text = (result.Content[0] as TextContentBlock)?.Text;
+        Assert.Equal(BaseAddress, text);
+    }
+
+    [McpServerToolType]
+    private sealed class PetsService(HttpClient httpClient)
+    {
+        [McpServerTool(Name = ToolName)]
+        [Description("List all pets")]
+        public string GetBaseAddress()
+        {
+            // Returning HttpClient.BaseAddress for verification
+            return httpClient.BaseAddress?.ToString() ?? string.Empty;
+        }
+    }
+}

tests/ModelContextProtocol.Tests/ModelContextProtocol.Tests.csproj

@@ -43,6 +43,7 @@
     </PackageReference>
     <PackageReference Include="Microsoft.Extensions.AI" />
     <PackageReference Include="Microsoft.Extensions.AI.OpenAI" />
+    <PackageReference Include="Microsoft.Extensions.Http" />
     <PackageReference Include="Microsoft.Extensions.Logging" />
     <PackageReference Include="Microsoft.Extensions.Logging.Console" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" />