chore: import upstream snapshot with attribution

dotnet/samples/02-agents/AgentProviders/foundry/Agent_Step03_UsingFunctionTools/Agent_Step03_UsingFunctionTools.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFrameworks>net10.0</TargetFrameworks>
+
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\..\..\src\Microsoft.Agents.AI.Foundry\Microsoft.Agents.AI.Foundry.csproj" />
+  </ItemGroup>
+
+</Project>

dotnet/samples/02-agents/AgentProviders/foundry/Agent_Step03_UsingFunctionTools/Program.cs

@@ -0,0 +1,41 @@
+// 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);
+}

dotnet/samples/02-agents/AgentProviders/foundry/Agent_Step03_UsingFunctionTools/README.md

@@ -0,0 +1,38 @@
+# Using Function Tools with the Responses API
+
+This sample demonstrates how to use function tools with the `ChatClientAgent`, allowing the agent to call custom functions to retrieve information.
+
+## What this sample demonstrates
+
+- Creating function tools using `AIFunctionFactory`
+- Passing function tools to a `ChatClientAgent`
+- Running agents with function tools (text output)
+- Running agents with function tools (streaming output)
+- No server-side agent creation or cleanup required
+
+## Prerequisites
+
+Before you begin, ensure you have the following prerequisites:
+
+- .NET 10 SDK or later
+- Microsoft Foundry service endpoint and deployment configured
+- An authenticated Azure identity (for example, sign in with `az login`)
+
+**Note**: This sample uses `DefaultAzureCredential`. `az login` is the easiest local development path, but Visual Studio, VS Code, and managed identity credentials also work when available.
+
+Set the following environment variables:
+
+```powershell
+$env:FOUNDRY_PROJECT_ENDPOINT="https://your-foundry-service.services.ai.azure.com/api/projects/your-foundry-project"
+$env:FOUNDRY_MODEL="gpt-5.4-mini"
+```
+
+## Run the sample
+
+Navigate to the Foundry sample directory and run:
+
+```powershell
+cd dotnet/samples/02-agents/AgentProviders/foundry
+dotnet run --project .\Agent_Step03_UsingFunctionTools
+```
+