Add McpServerPrompt / McpClientPrompt and friends

Author: stephentoub

Diff for: README.md

@@ -84,9 +84,9 @@ the employed overload of `WithTools` examines the current assembly for classes w
 `McpTool` attribute as tools.)
 
 ```csharp
-using ModelContextProtocol;
-using ModelContextProtocol.Server;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
+using ModelContextProtocol.Server;
 using System.ComponentModel;
 
 var builder = Host.CreateEmptyApplicationBuilder(settings: null);
@@ -109,7 +109,7 @@ the connected client. Similarly, arguments may be injected via dependency inject
 `IMcpServer` to make sampling requests back to the client in order to summarize content it downloads from the specified url via
 an `HttpClient` injected via dependency injection.
 ```csharp
-[McpServerTool("SummarizeContentFromUrl"), Description("Summarizes content downloaded from a specific URI")]
+[McpServerTool(Name = "SummarizeContentFromUrl"), Description("Summarizes content downloaded from a specific URI")]
 public static async Task<string> SummarizeDownloadedContent(
     IMcpServer thisServer,
     HttpClient httpClient,
@@ -122,8 +122,8 @@ public static async Task<string> SummarizeDownloadedContent(
     [
         new(ChatRole.User, "Briefly summarize the following downloaded content:"),
         new(ChatRole.User, content),
-    ]
-
+    ];
+    
     ChatOptions options = new()
     {
         MaxOutputTokens = 256,
@@ -134,13 +134,24 @@ public static async Task<string> SummarizeDownloadedContent(
 }
 ```
 
+Prompts can be exposed in a similar manner, using `[McpServerPrompt]`, e.g.
+```csharp
+[McpServerPromptType]
+public static class MyPrompts
+{
+    [McpServerPrompt, Description("Creates a prompt to summarize the provided message.")]
+    public static ChatMessage Summarize([Description("The content to summarize")] string content) =>
+        new(ChatRole.User, $"Please summarize this content into a single sentence: {content}");
+}
+```
+
 More control is also available, with fine-grained control over configuring the server and how it should handle client requests. For example:
 
 ```csharp
 using ModelContextProtocol.Protocol.Transport;
 using ModelContextProtocol.Protocol.Types;
 using ModelContextProtocol.Server;
-using Microsoft.Extensions.Logging.Abstractions;
+using System.Text.Json;
 
 McpServerOptions options = new()
 {
@@ -149,9 +160,8 @@ McpServerOptions options = new()
     {
         Tools = new()
         {
-            ListToolsHandler = async (request, cancellationToken) =>
-            {
-                return new ListToolsResult()
+            ListToolsHandler = (request, cancellationToken) =>
+                Task.FromResult(new ListToolsResult()
                 {
                     Tools =
                     [
@@ -173,10 +183,9 @@ McpServerOptions options = new()
                                 """),
                         }
                     ]
-                };
-            },
+                }),
 
-            CallToolHandler = async (request, cancellationToken) =>
+            CallToolHandler = (request, cancellationToken) =>
             {
                 if (request.Params?.Name == "echo")
                 {
@@ -185,10 +194,10 @@ McpServerOptions options = new()
                         throw new McpServerException("Missing required argument 'message'");
                     }
 
-                    return new CallToolResponse()
+                    return Task.FromResult(new CallToolResponse()
                     {
                         Content = [new Content() { Text = $"Echo: {message}", Type = "text" }]
-                    };
+                    });
                 }
 
                 throw new McpServerException($"Unknown tool: '{request.Params?.Name}'");

Diff for: samples/AspNetCoreSseServer/Program.cs

@@ -1,4 +1,3 @@
-using ModelContextProtocol;
 using AspNetCoreSseServer;
 
 var builder = WebApplication.CreateBuilder(args);

Diff for: samples/QuickstartWeatherServer/Program.cs

@@ -1,6 +1,5 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
-using ModelContextProtocol;
 using System.Net.Http.Headers;
 
 var builder = Host.CreateEmptyApplicationBuilder(settings: null);

Diff for: samples/TestServerWithHosting/Program.cs

@@ -1,4 +1,4 @@
-using ModelContextProtocol;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Serilog;
 

Diff for: src/ModelContextProtocol/AIContentExtensions.cs

@@ -25,6 +25,37 @@ public static ChatMessage ToChatMessage(this PromptMessage promptMessage)
         };
     }
 
+    /// <summary>Creates <see cref="ChatMessage"/>s from a <see cref="GetPromptResult"/>.</summary>
+    /// <param name="promptResult">The messages to convert.</param>
+    /// <returns>The created <see cref="ChatMessage"/>.</returns>
+    public static IList<ChatMessage> ToChatMessages(this GetPromptResult promptResult)
+    {
+        Throw.IfNull(promptResult);
+
+        return promptResult.Messages.Select(m => m.ToChatMessage()).ToList();
+    }
+
+    /// <summary>Gets <see cref="PromptMessage"/> instances for the specified <see cref="ChatMessage"/>.</summary>
+    /// <param name="chatMessage">The message for which to extract its contents as <see cref="PromptMessage"/> instances.</param>
+    /// <returns>The converted content.</returns>
+    public static IList<PromptMessage> ToPromptMessages(this ChatMessage chatMessage)
+    {
+        Throw.IfNull(chatMessage);
+
+        Role r = chatMessage.Role == ChatRole.User ? Role.User : Role.Assistant;
+
+        List<PromptMessage> messages = [];
+        foreach (var content in chatMessage.Contents)
+        {
+            if (content is TextContent or DataContent)
+            {
+                messages.Add(new PromptMessage { Role = r, Content = content.ToContent() });
+            }
+        }
+
+        return messages;
+    }
+
     /// <summary>Creates a new <see cref="AIContent"/> from the content of a <see cref="Content"/>.</summary>
     /// <param name="content">The <see cref="Content"/> to convert.</param>
     /// <returns>The created <see cref="AIContent"/>.</returns>

Diff for: src/ModelContextProtocol/Client/McpClient.cs

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

Diff for: src/ModelContextProtocol/Client/McpClientExtensions.cs

@@ -115,27 +115,23 @@ public static async IAsyncEnumerable<McpClientTool> EnumerateToolsAsync(
     /// <param name="client">The client.</param>
     /// <param name="cancellationToken">A token to cancel the operation.</param>
     /// <returns>A list of all available prompts.</returns>
-    public static async Task<IList<Prompt>> ListPromptsAsync(
+    public static async Task<IList<McpClientPrompt>> ListPromptsAsync(
         this IMcpClient client, CancellationToken cancellationToken = default)
     {
         Throw.IfNull(client);
 
-        List<Prompt>? prompts = null;
-
+        List<McpClientPrompt>? prompts = null;
         string? cursor = null;
         do
         {
             var promptResults = await client.SendRequestAsync<ListPromptsResult>(
                 CreateRequest(RequestMethods.PromptsList, CreateCursorDictionary(cursor)),
                 cancellationToken).ConfigureAwait(false);
 
-            if (prompts is null)
-            {
-                prompts = promptResults.Prompts;
-            }
-            else
+            prompts ??= new List<McpClientPrompt>(promptResults.Prompts.Count);
+            foreach (var prompt in promptResults.Prompts)
             {
-                prompts.AddRange(promptResults.Prompts);
+                prompts.Add(new McpClientPrompt(client, prompt));
             }
 
             cursor = promptResults.NextCursor;
@@ -186,7 +182,7 @@ public static async IAsyncEnumerable<Prompt> EnumeratePromptsAsync(
     /// <param name="cancellationToken">A token to cancel the operation.</param>
     /// <returns>A task containing the prompt's content and messages.</returns>
     public static Task<GetPromptResult> GetPromptAsync(
-        this IMcpClient client, string name, Dictionary<string, object?>? arguments = null, CancellationToken cancellationToken = default)
+        this IMcpClient client, string name, IReadOnlyDictionary<string, object?>? arguments = null, CancellationToken cancellationToken = default)
     {
         Throw.IfNull(client);
         Throw.IfNullOrWhiteSpace(name);
@@ -345,7 +341,7 @@ public static Task<ReadResourceResult> ReadResourceAsync(
         Throw.IfNullOrWhiteSpace(uri);
 
         return client.SendRequestAsync<ReadResourceResult>(
-            CreateRequest(RequestMethods.ResourcesRead, new() { ["uri"] = uri }),
+            CreateRequest(RequestMethods.ResourcesRead, new Dictionary<string, object?>() { ["uri"] = uri }),
             cancellationToken);
     }
 
@@ -369,7 +365,7 @@ public static Task<CompleteResult> GetCompletionAsync(this IMcpClient client, Re
         }
 
         return client.SendRequestAsync<CompleteResult>(
-            CreateRequest(RequestMethods.CompletionComplete, new()
+            CreateRequest(RequestMethods.CompletionComplete, new Dictionary<string, object?>()
             {
                 ["ref"] = reference,
                 ["argument"] = new Argument { Name = argumentName, Value = argumentValue }
@@ -389,7 +385,7 @@ public static Task SubscribeToResourceAsync(this IMcpClient client, string uri,
         Throw.IfNullOrWhiteSpace(uri);
 
         return client.SendRequestAsync<EmptyResult>(
-            CreateRequest(RequestMethods.ResourcesSubscribe, new() { ["uri"] = uri }),
+            CreateRequest(RequestMethods.ResourcesSubscribe, new Dictionary<string, object?>() { ["uri"] = uri }),
             cancellationToken);
     }
 
@@ -405,7 +401,7 @@ public static Task UnsubscribeFromResourceAsync(this IMcpClient client, string u
         Throw.IfNullOrWhiteSpace(uri);
 
         return client.SendRequestAsync<EmptyResult>(
-            CreateRequest(RequestMethods.ResourcesUnsubscribe, new() { ["uri"] = uri }),
+            CreateRequest(RequestMethods.ResourcesUnsubscribe, new Dictionary<string, object?>() { ["uri"] = uri }),
             cancellationToken);
     }
 
@@ -560,11 +556,11 @@ public static Task SetLoggingLevel(this IMcpClient client, LoggingLevel level, C
         Throw.IfNull(client);
 
         return client.SendRequestAsync<EmptyResult>(
-            CreateRequest(RequestMethods.LoggingSetLevel, new() { ["level"] = level }),
+            CreateRequest(RequestMethods.LoggingSetLevel, new Dictionary<string, object?>() { ["level"] = level }),
             cancellationToken);
     }
 
-    private static JsonRpcRequest CreateRequest(string method, Dictionary<string, object?>? parameters) =>
+    private static JsonRpcRequest CreateRequest(string method, IReadOnlyDictionary<string, object?>? parameters) =>
         new()
         {
             Method = method,

Diff for: src/ModelContextProtocol/Client/McpClientFactory.cs

@@ -1,6 +1,5 @@
 using System.Globalization;
 using System.Runtime.InteropServices;
-using ModelContextProtocol.Configuration;
 using ModelContextProtocol.Logging;
 using ModelContextProtocol.Protocol.Transport;
 using ModelContextProtocol.Utils;

Diff for: src/ModelContextProtocol/Client/McpClientPrompt.cs

@@ -0,0 +1,41 @@
+using ModelContextProtocol.Protocol.Types;
+
+namespace ModelContextProtocol.Client;
+
+/// <summary>Provides an invocable prompt.</summary>
+public sealed class McpClientPrompt
+{
+    private readonly IMcpClient _client;
+
+    internal McpClientPrompt(IMcpClient client, Prompt prompt)
+    {
+        _client = client;
+        ProtocolPrompt = prompt;
+    }
+
+    /// <summary>Gets the protocol <see cref="Prompt"/> type for this instance.</summary>
+    public Prompt ProtocolPrompt { get; }
+
+    /// <summary>
+    /// Retrieves a specific prompt with optional arguments.
+    /// </summary>
+    /// <param name="arguments">Optional arguments for the prompt</param>
+    /// <param name="cancellationToken">A token to cancel the operation.</param>
+    /// <returns>A task containing the prompt's content and messages.</returns>
+    public async ValueTask<GetPromptResult> GetAsync(
+        IEnumerable<KeyValuePair<string, object?>>? arguments = null,
+        CancellationToken cancellationToken = default)
+    {
+        IReadOnlyDictionary<string, object?>? argDict =
+            arguments as IReadOnlyDictionary<string, object?> ??
+            arguments?.ToDictionary();
+
+        return await _client.GetPromptAsync(ProtocolPrompt.Name, argDict, cancellationToken).ConfigureAwait(false);
+    }
+
+    /// <summary>Gets the name of the prompt.</summary>
+    public string Name => ProtocolPrompt.Name;
+
+    /// <summary>Gets a description of the prompt.</summary>
+    public string? Description => ProtocolPrompt.Description;
+}

Diff for: src/ModelContextProtocol/Configuration/DefaultMcpServerBuilder.cs

@@ -1,12 +1,11 @@
 using ModelContextProtocol.Utils;
-using Microsoft.Extensions.DependencyInjection;
 
-namespace ModelContextProtocol.Configuration;
+namespace Microsoft.Extensions.DependencyInjection;
 
 /// <summary>
 /// Default implementation of <see cref="IMcpServerBuilder"/>.
 /// </summary>
-internal class DefaultMcpServerBuilder : IMcpServerBuilder
+internal sealed class DefaultMcpServerBuilder : IMcpServerBuilder
 {
     /// <inheritdoc/>
     public IServiceCollection Services { get; }

Diff for: src/ModelContextProtocol/Configuration/IMcpServerBuilder.cs

@@ -1,7 +1,6 @@
 using ModelContextProtocol.Server;
-using Microsoft.Extensions.DependencyInjection;
 
-namespace ModelContextProtocol.Configuration;
+namespace Microsoft.Extensions.DependencyInjection;
 
 /// <summary>
 /// Builder for configuring <see cref="IMcpServer"/> instances.