agent-as-mcp-tool

Expose an agent as an MCP tool

::: zone pivot="programming-language-csharp"

This tutorial shows you how to expose an agent as a tool over the Model Context Protocol (MCP), so it can be used by other systems that support MCP tools.

Prerequisites

For prerequisites see the Create and run a simple agent step in this tutorial.

Install NuGet packages

To use Microsoft Agent Framework with Azure OpenAI, you need to install the following NuGet packages:

dotnet add package Azure.AI.OpenAI --prerelease
dotnet add package Azure.Identity
dotnet add package Microsoft.Agents.AI.OpenAI --prerelease

To also add support for hosting a tool over the Model Context Protocol (MCP), add the following NuGet packages

dotnet add package Microsoft.Extensions.Hosting --prerelease
dotnet add package ModelContextProtocol --prerelease

Expose an agent as an MCP tool

You can expose an AIAgent as an MCP tool by wrapping it in a function and using McpServerTool. You then need to register it with an MCP server. This allows the agent to be invoked as a tool by any MCP-compatible client.

First, create an agent that you'll expose as an MCP tool.

using System;
using Azure.AI.OpenAI;
using Azure.Identity;
using Microsoft.Agents.AI;
using OpenAI;

AIAgent agent = new AzureOpenAIClient(
    new Uri("https://<myresource>.openai.azure.com"),
    new AzureCliCredential())
        .GetChatClient("gpt-4o-mini")
        .AsAIAgent(instructions: "You are good at telling jokes.", name: "Joker");

Turn the agent into a function tool and then an MCP tool. The agent name and description will be used as the mcp tool name and description.

using ModelContextProtocol.Server;

McpServerTool tool = McpServerTool.Create(agent.AsAIFunction());

Setup the MCP server to listen for incoming requests over standard input/output and expose the MCP tool:

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using ModelContextProtocol.Server;

HostApplicationBuilder builder = Host.CreateEmptyApplicationBuilder(settings: null);
builder.Services
    .AddMcpServer()
    .WithStdioServerTransport()
    .WithTools([tool]);

await builder.Build().RunAsync();