Create a minimal MCP client using .NET

In this quickstart, you build a minimal Model Context Protocol (MCP) client using the C# SDK for MCP. You also learn how to configure the client to connect to an MCP server, such as the one created in the Build a minimal MCP server quickstart.

Prerequisites

• .NET 8.0 SDK or higher
• Visual Studio Code

Create the .NET host app

Complete the following steps to create a .NET console app. The app acts as a host for an MCP client that connects to an MCP server.

Create the project

1. In a terminal window, navigate to the directory where you want to create your app, and create a new console app with the dotnet new command:

   dotnet new console -n MCPHostApp
   

2. Navigate into the newly created project folder:

   cd MCPHostApp
   

3. Run the following commands to add the necessary NuGet packages:

   dotnet add package Azure.AI.OpenAI --prerelease
   dotnet add package Azure.Identity
   dotnet add package Microsoft.Extensions.AI
   dotnet add package Microsoft.Extensions.AI.OpenAI --prerelease
   dotnet add package ModelContextProtocol --prerelease
   

4. Open the project folder in your editor of choice, such as Visual Studio Code:

   code .
   

Add the app code

Replace the contents of Program.cs with the following code:

using Azure.AI.OpenAI;
using Azure.Identity;
using Microsoft.Extensions.AI;
using ModelContextProtocol.Client;

// Create an IChatClient using Azure OpenAI.
IChatClient client =
    new ChatClientBuilder(
        new AzureOpenAIClient(new Uri("<your-azure-openai-endpoint>"),
        new DefaultAzureCredential())
        .GetChatClient("gpt-4o").AsIChatClient())
    .UseFunctionInvocation()
    .Build();

// Create the MCP client
// Configure it to start and connect to your MCP server.
IMcpClient mcpClient = await McpClientFactory.CreateAsync(
    new StdioClientTransport(new()
    {
        Command = "dotnet run",
        Arguments = ["--project", "<path-to-your-mcp-server-project>"],
        Name = "Minimal MCP Server",
    }));

// List all available tools from the MCP server.
Console.WriteLine("Available tools:");
IList<McpClientTool> tools = await mcpClient.ListToolsAsync();
foreach (McpClientTool tool in tools)
{
    Console.WriteLine($"{tool}");
}
Console.WriteLine();

// Conversational loop that can utilize the tools via prompts.
List<ChatMessage> messages = [];
while (true)
{
    Console.Write("Prompt: ");
    messages.Add(new(ChatRole.User, Console.ReadLine()));

    List<ChatResponseUpdate> updates = [];
    await foreach (ChatResponseUpdate update in client
        .GetStreamingResponseAsync(messages, new() { Tools = [.. tools] }))
    {
        Console.Write(update);
        updates.Add(update);
    }
    Console.WriteLine();

    messages.AddMessages(updates);
}

The preceding code accomplishes the following tasks:

• Initializes an IChatClient abstraction using the Microsoft.Extensions.AI libraries.
• Creates an MCP client and configures it to connect to your MCP server.
• Retrieves and displays a list of available tools from the MCP server, which is a standard MCP function.
• Implements a conversational loop that processes user prompts and utilizes the tools for responses.

Run and test the app

Complete the following steps to test your .NET host app:

1. In a terminal window open to the root of your project, run the following command to start the app:

   dotnet run
   

2. Once the app is running, enter a prompt to run the ReverseEcho tool:

   Reverse the following: "Hello, minimal MCP server!"
   

3. Verify that the server responds with the echoed message:

   !revres PCM laminim ,olleH
   

Related content

Get started with .NET AI and the Model Context Protocol