.Net: MCP prompt sample (#11342)

### Motivation, Context and Description

This PR adds sample showing how to power MCP prompt by SK prompt server
side and consume this prompt client side.

Contributes to:
#11199

---------

Co-authored-by: westey <[email protected]>

Author: SergeyMenshykh

dotnet/samples/Demos/ModelContextProtocolClientServer/MCPClient/Extensions/PromptResultExtensions.cs

@@ -0,0 +1,45 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using Microsoft.SemanticKernel;
+using Microsoft.SemanticKernel.ChatCompletion;
+using ModelContextProtocol.Protocol.Types;
+
+namespace MCPClient;
+
+/// <summary>
+/// Extension methods for <see cref="GetPromptResult"/>.
+/// </summary>
+internal static class PromptResultExtensions
+{
+    /// <summary>
+    /// Converts a <see cref="GetPromptResult"/> to a <see cref="ChatHistory"/>.
+    /// </summary>
+    /// <param name="result">The prompt result to convert.</param>
+    /// <returns>The corresponding <see cref="ChatHistory"/>.</returns>
+    public static ChatHistory ToChatHistory(this GetPromptResult result)
+    {
+        ChatHistory chatHistory = [];
+
+        foreach (PromptMessage message in result.Messages)
+        {
+            ChatMessageContentItemCollection items = [];
+
+            switch (message.Content.Type)
+            {
+                case "text":
+                    items.Add(new TextContent(message.Content.Text));
+                    break;
+                case "image":
+                    items.Add(new ImageContent(Convert.FromBase64String(message.Content.Data!), message.Content.MimeType));
+                    break;
+                default:
+                    throw new InvalidOperationException($"Unexpected message content type '{message.Content.Type}'");
+            }
+
+            chatHistory.Add(new ChatMessageContent(message.Role.ToAuthorRole(), items));
+        }
+
+        return chatHistory;
+    }
+}

dotnet/samples/Demos/ModelContextProtocolClientServer/MCPClient/Extensions/RoleExtensions.cs

@@ -0,0 +1,28 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using Microsoft.SemanticKernel.ChatCompletion;
+using ModelContextProtocol.Protocol.Types;
+
+namespace MCPClient;
+
+/// <summary>
+/// Extension methods for the <see cref="Role"/> enum.
+/// </summary>
+internal static class RoleExtensions
+{
+    /// <summary>
+    /// Converts a <see cref="Role"/> to a <see cref="AuthorRole"/>.
+    /// </summary>
+    /// <param name="role">The MCP role to convert.</param>
+    /// <returns>The corresponding <see cref="AuthorRole"/>.</returns>
+    public static AuthorRole ToAuthorRole(this Role role)
+    {
+        return role switch
+        {
+            Role.User => AuthorRole.User,
+            Role.Assistant => AuthorRole.Assistant,
+            _ => throw new InvalidOperationException($"Unexpected role '{role}'")
+        };
+    }
+}

dotnet/samples/Demos/ModelContextProtocolClientServer/MCPClient/Program.cs

@@ -7,17 +7,41 @@
 using System.Threading.Tasks;
 using Microsoft.Extensions.Configuration;
 using Microsoft.SemanticKernel;
+using Microsoft.SemanticKernel.ChatCompletion;
 using Microsoft.SemanticKernel.Connectors.OpenAI;
 using ModelContextProtocol;
 using ModelContextProtocol.Client;
 using ModelContextProtocol.Protocol.Transport;
+using ModelContextProtocol.Protocol.Types;
 
 namespace MCPClient;
 
 internal sealed class Program
 {
     public static async Task Main(string[] args)
     {
+        // Use the MCP tools with the Semantic Kernel
+        await UseMCPToolsWithSKAsync();
+
+        // Use the MCP tools and MCP prompt with the Semantic Kernel
+        await UseMCPToolsAndPromptWithSKAsync();
+    }
+
+    /// <summary>
+    /// Demonstrates how to use the MCP tools with the Semantic Kernel.
+    /// The code in this method:
+    /// 1. Creates an MCP client.
+    /// 2. Retrieves the list of tools provided by the MCP server.
+    /// 3. Creates a kernel and registers the MCP tools as Kernel functions.
+    /// 4. Sends the prompt to AI model together with the MCP tools represented as Kernel functions.
+    /// 5. The AI model calls DateTimeUtils-GetCurrentDateTimeInUtc function to get the current date time in UTC required as an argument for the next function.
+    /// 6. The AI model calls WeatherUtils-GetWeatherForCity function with the current date time and the `Boston` arguments extracted from the prompt to get the weather information.
+    /// 7. Having received the weather information from the function call, the AI model returns the answer to the prompt.
+    /// </summary>
+    private static async Task UseMCPToolsWithSKAsync()
+    {
+        Console.WriteLine($"Running the {nameof(UseMCPToolsWithSKAsync)} sample.");
+
         // Create an MCP client
         await using IMcpClient mcpClient = await CreateMcpClientAsync();
 
@@ -43,10 +67,67 @@ public static async Task Main(string[] args)
         FunctionResult result = await kernel.InvokePromptAsync(prompt, new(executionSettings));
 
         Console.WriteLine(result);
+        Console.WriteLine();
 
         // The expected output is: The likely color of the sky in Boston today is gray, as it is currently rainy.
     }
 
+    /// <summary>
+    /// Demonstrates how to use the MCP tools and MCP prompt with the Semantic Kernel.
+    /// The code in this method:
+    /// 1. Creates an MCP client.
+    /// 2. Retrieves the list of tools provided by the MCP server.
+    /// 3. Retrieves the list of prompts provided by the MCP server.
+    /// 4. Creates a kernel and registers the MCP tools as Kernel functions.
+    /// 5. Requests the `GetCurrentWeatherForCity` prompt from the MCP server.
+    /// 6. The MCP server renders the prompt using the `Boston` as value for the `city` parameter and the result of the `DateTimeUtils-GetCurrentDateTimeInUtc` server-side invocation added to the prompt as part of prompt rendering.
+    /// 7. Converts the MCP server prompt: list of messages where each message is represented by content and role to a chat history.
+    /// 8. Sends the chat history to the AI model together with the MCP tools represented as Kernel functions.
+    /// 9. The AI model calls WeatherUtils-GetWeatherForCity function with the current date time and the `Boston` arguments extracted from the prompt to get the weather information.
+    /// 10. Having received the weather information from the function call, the AI model returns the answer to the prompt.
+    /// </summary>
+    private static async Task UseMCPToolsAndPromptWithSKAsync()
+    {
+        Console.WriteLine($"Running the {nameof(UseMCPToolsAndPromptWithSKAsync)} sample.");
+
+        // Create an MCP client
+        await using IMcpClient mcpClient = await CreateMcpClientAsync();
+
+        // Retrieve and display the list provided by the MCP server
+        IList<McpClientTool> tools = await mcpClient.ListToolsAsync();
+        DisplayTools(tools);
+
+        // Retrieve and display the list of prompts provided by the MCP server
+        IList<McpClientPrompt> prompts = await mcpClient.ListPromptsAsync();
+        DisplayPrompts(prompts);
+
+        // Create a kernel and register the MCP tools
+        Kernel kernel = CreateKernelWithChatCompletionService();
+        kernel.Plugins.AddFromFunctions("Tools", tools.Select(aiFunction => aiFunction.AsKernelFunction()));
+
+        // Enable automatic function calling
+        OpenAIPromptExecutionSettings executionSettings = new()
+        {
+            Temperature = 0,
+            FunctionChoiceBehavior = FunctionChoiceBehavior.Auto(options: new() { RetainArgumentTypes = true })
+        };
+
+        // Retrieve the `GetCurrentWeatherForCity` prompt from the MCP server and convert it to a chat history
+        GetPromptResult promptResult = await mcpClient.GetPromptAsync("GetCurrentWeatherForCity", new Dictionary<string, object?>() { ["city"] = "Boston" });
+
+        ChatHistory chatHistory = promptResult.ToChatHistory();
+
+        // Execute a prompt using the MCP tools and prompt
+        IChatCompletionService chatCompletion = kernel.GetRequiredService<IChatCompletionService>();
+
+        ChatMessageContent result = await chatCompletion.GetChatMessageContentAsync(chatHistory, executionSettings, kernel);
+
+        Console.WriteLine(result);
+        Console.WriteLine();
+
+        // The expected output is: The weather in Boston as of 2025-04-02 16:39:40 is 61°F and rainy.
+    }
+
     /// <summary>
     /// Creates an instance of <see cref="Kernel"/> with the OpenAI chat completion service registered.
     /// </summary>
@@ -129,5 +210,20 @@ private static void DisplayTools(IList<McpClientTool> tools)
         {
             Console.WriteLine($"- {tool.Name}: {tool.Description}");
         }
+        Console.WriteLine();
+    }
+
+    /// <summary>
+    /// Displays the list of available MCP prompts.
+    /// </summary>
+    /// <param name="prompts">The list of the prompts to display.</param>
+    private static void DisplayPrompts(IList<McpClientPrompt> prompts)
+    {
+        Console.WriteLine("Available MCP prompts:");
+        foreach (var prompt in prompts)
+        {
+            Console.WriteLine($"- {prompt.Name}: {prompt.Description}");
+        }
+        Console.WriteLine();
     }
 }

dotnet/samples/Demos/ModelContextProtocolClientServer/MCPServer/MCPServer.csproj

@@ -7,12 +7,21 @@
     <NoWarn>$(NoWarn);VSTHRD111;CA2007;SKEXP0001</NoWarn>
   </PropertyGroup>
 
+  <ItemGroup>
+    <Content Remove="Prompts\getCurrentWeatherForCity.json" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <EmbeddedResource Include="Prompts\getCurrentWeatherForCity.json" />
+  </ItemGroup>
+
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Hosting" />
     <PackageReference Include="ModelContextProtocol" />
   </ItemGroup>
 
   <ItemGroup>
+    <ProjectReference Include="..\..\..\..\src\Extensions\PromptTemplates.Handlebars\PromptTemplates.Handlebars.csproj" />
     <ProjectReference Include="..\..\..\..\src\SemanticKernel.Abstractions\SemanticKernel.Abstractions.csproj" />
     <ProjectReference Include="..\..\..\..\src\SemanticKernel.Core\SemanticKernel.Core.csproj" />
   </ItemGroup>

dotnet/samples/Demos/ModelContextProtocolClientServer/MCPServer/Program.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 
 using MCPServer;
+using MCPServer.Prompts;
 using MCPServer.Tools;
 using Microsoft.SemanticKernel;
 
@@ -12,10 +13,16 @@
 // Build the kernel
 Kernel kernel = kernelBuilder.Build();
 
+// Register prompts
+PromptRegistry.RegisterPrompt(PromptDefinition.Create(EmbeddedResource.ReadAsString("getCurrentWeatherForCity.json"), kernel));
+
 var builder = Host.CreateEmptyApplicationBuilder(settings: null);
 builder.Services
     .AddMcpServer()
     .WithStdioServerTransport()
     // Add all functions from the kernel plugins to the MCP server as tools
-    .WithTools(kernel.Plugins);
+    .WithTools(kernel.Plugins)
+    // Register prompt handlers
+    .WithListPromptsHandler(PromptRegistry.HandlerListPromptRequestsAsync)
+    .WithGetPromptHandler(PromptRegistry.HandlerGetPromptRequestsAsync);
 await builder.Build().RunAsync();

dotnet/samples/Demos/ModelContextProtocolClientServer/MCPServer/Prompts/EmbeddedResource.cs

@@ -0,0 +1,32 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Reflection;
+
+namespace MCPServer.Prompts;
+
+/// <summary>
+/// Reads embedded resources.
+/// </summary>
+public static class EmbeddedResource
+{
+    private static readonly string? s_namespace = typeof(EmbeddedResource).Namespace;
+
+    internal static string ReadAsString(string fileName)
+    {
+        // Get the current assembly. Note: this class is in the same assembly where the embedded resources are stored.
+        Assembly assembly =
+            typeof(EmbeddedResource).GetTypeInfo().Assembly ??
+            throw new InvalidOperationException($"[{s_namespace}] {fileName} assembly not found");
+
+        // Resources are mapped like types, using the namespace and appending "." (dot) and the file name
+        string resourceName = $"{s_namespace}.{fileName}";
+
+        Stream stream =
+            assembly.GetManifestResourceStream(resourceName) ??
+            throw new InvalidOperationException($"{resourceName} resource not found");
+
+        // Return the resource content, in text format.
+        using StreamReader reader = new(stream);
+        return reader.ReadToEnd();
+    }
+}

dotnet/samples/Demos/ModelContextProtocolClientServer/MCPServer/Prompts/PromptDefinition.cs

@@ -0,0 +1,111 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using Microsoft.SemanticKernel;
+using Microsoft.SemanticKernel.PromptTemplates.Handlebars;
+using ModelContextProtocol.Protocol.Types;
+using ModelContextProtocol.Server;
+
+namespace MCPServer.Prompts;
+
+/// <summary>
+/// Represents a prompt definition.
+/// </summary>
+internal sealed class PromptDefinition
+{
+    /// <summary>
+    /// Gets or sets the prompt.
+    /// </summary>
+    public required Prompt Prompt { get; init; }
+
+    /// <summary>
+    /// Gets or sets the handler for the prompt.
+    /// </summary>
+    public required Func<RequestContext<GetPromptRequestParams>, CancellationToken, Task<GetPromptResult>> Handler { get; init; }
+
+    /// <summary>
+    /// Gets this prompt definition.
+    /// </summary>
+    /// <param name="jsonPrompt">The JSON prompt template.</param>
+    /// <param name="kernel">An instance of the kernel to render the prompt.</param>
+    /// <returns>The prompt definition.</returns>
+    public static PromptDefinition Create(string jsonPrompt, Kernel kernel)
+    {
+        PromptTemplateConfig promptTemplateConfig = PromptTemplateConfig.FromJson(jsonPrompt);
+
+        return new PromptDefinition()
+        {
+            Prompt = GetPrompt(promptTemplateConfig),
+            Handler = (context, cancellationToken) =>
+            {
+                IPromptTemplate promptTemplate = new HandlebarsPromptTemplateFactory().Create(promptTemplateConfig);
+
+                return GetPromptHandlerAsync(context, promptTemplateConfig, promptTemplate, kernel, cancellationToken);
+            }
+        };
+    }
+
+    /// <summary>
+    /// Creates an MCP prompt from SK prompt template.
+    /// </summary>
+    /// <param name="promptTemplateConfig">The prompt template configuration.</param>
+    /// <returns>The MCP prompt.</returns>
+    private static Prompt GetPrompt(PromptTemplateConfig promptTemplateConfig)
+    {
+        // Create the MCP prompt arguments
+        List<PromptArgument>? arguments = null;
+
+        foreach (var inputVariable in promptTemplateConfig.InputVariables)
+        {
+            (arguments ??= []).Add(new()
+            {
+                Name = inputVariable.Name,
+                Description = inputVariable.Description,
+                Required = inputVariable.IsRequired
+            });
+        }
+
+        // Create the MCP prompt
+        return new Prompt
+        {
+            Name = promptTemplateConfig.Name!,
+            Description = promptTemplateConfig.Description,
+            Arguments = arguments
+        };
+    }
+
+    /// <summary>
+    /// Handles the prompt request by rendering the prompt.
+    /// </summary>
+    /// <param name="context">The MCP request context.</param>
+    /// <param name="promptTemplateConfig">The prompt template configuration.</param>
+    /// <param name="promptTemplate">The prompt template.</param>
+    /// <param name="kernel">The kernel to render the prompt.</param>
+    /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>The prompt.</returns>
+    private static async Task<GetPromptResult> GetPromptHandlerAsync(RequestContext<GetPromptRequestParams> context, PromptTemplateConfig promptTemplateConfig, IPromptTemplate promptTemplate, Kernel kernel, CancellationToken cancellationToken)
+    {
+        // Render the prompt
+        string renderedPrompt = await promptTemplate.RenderAsync(
+            kernel: kernel,
+            arguments: context.Params?.Arguments is { } args ? new KernelArguments(args!) : null,
+            cancellationToken: cancellationToken);
+
+        // Create prompt result
+        return new GetPromptResult()
+        {
+            Description = promptTemplateConfig.Description,
+            Messages =
+            [
+                new PromptMessage()
+                {
+                    Content = new Content()
+                    {
+                        Type = "text",
+                        Text = renderedPrompt
+                    },
+                    Role = Role.User
+                }
+            ]
+        };
+    }
+}