agent-framework/dotnet/samples/02-agents/AgentsWithFoundry/Agent_Step03_UsingFunctionTools

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
• Azure CLI installed and authenticated (for Azure credential authentication)

Note: This demo uses Azure CLI credentials for authentication. Make sure you're logged in with az login and have access to the Microsoft Foundry resource. For more information, see the Azure CLI documentation.

Set the following environment variables:

$env:AZURE_AI_PROJECT_ENDPOINT="https://your-foundry-service.services.ai.azure.com/api/projects/your-foundry-project"
$env:AZURE_AI_MODEL_DEPLOYMENT_NAME="gpt-5.4-mini"

Run the sample

Navigate to the AgentsWithFoundry sample directory and run:

cd dotnet/samples/02-agents/AgentsWithFoundry
dotnet run --project .\Agent_Step03_UsingFunctionTools