agent-framework/dotnet/samples/02-agents/AgentsWithFoundry/Agent_Step03_UsingFunctionTools/Program.cs

// Copyright (c) Microsoft. All rights reserved.

// This sample demonstrates how to use function tools.

using System.ComponentModel;
using Azure.AI.Projects;
using Azure.Identity;
using Microsoft.Agents.AI;
using Microsoft.Extensions.AI;

[Description("Get the weather for a given location.")]
static string GetWeather([Description("The location to get the weather for.")] string location)
    => $"The weather in {location} is cloudy with a high of 15°C.";

// Define the function tool.
AITool tool = AIFunctionFactory.Create(GetWeather);

string endpoint = Environment.GetEnvironmentVariable("FOUNDRY_PROJECT_ENDPOINT") ?? throw new InvalidOperationException("FOUNDRY_PROJECT_ENDPOINT is not set.");
string deploymentName = Environment.GetEnvironmentVariable("FOUNDRY_MODEL") ?? "gpt-5.4-mini";

// WARNING: DefaultAzureCredential is convenient for development but requires careful consideration in production.
// In production, consider using a specific credential (e.g., ManagedIdentityCredential) to avoid
// latency issues, unintended credential probing, and potential security risks from fallback mechanisms.
AIProjectClient aiProjectClient = new(new Uri(endpoint), new DefaultAzureCredential());

// Create a AIAgent with function tools.
AIAgent agent = aiProjectClient.AsAIAgent(deploymentName,
    instructions: "You are a helpful assistant that can get weather information.",
    name: "WeatherAssistant",
    tools: [tool]);

// Non-streaming agent interaction with function tools.
AgentSession session = await agent.CreateSessionAsync();
Console.WriteLine(await agent.RunAsync("What is the weather like in Amsterdam?", session));

// Streaming agent interaction with function tools.
session = await agent.CreateSessionAsync();
await foreach (AgentResponseUpdate update in agent.RunStreamingAsync("What is the weather like in Amsterdam?", session))
{
    Console.Write(update);
}