Agent_Step20_DynamicFunctionTools

Dynamic Function Tools

This sample demonstrates how to dynamically expand the set of function tools available to an agent during a function-calling loop.

What it demonstrates

• The agent starts with only a single RequestTools function
• When the model needs capabilities it doesn't have, it calls RequestTools with a description of the functionality needed
• The RequestTools function uses the ambient FunctionInvokingChatClient.CurrentContext to access ChatOptions.Tools and add new tools at runtime
• The agent then uses the newly added tools in subsequent iterations of the same function-calling loop

How it works

1. A tool catalog maps keywords (e.g. "weather", "time", "temperature") to pre-built AIFunction instances
2. The RequestTools function matches the description against catalog keywords and adds matching tools to ChatOptions.Tools
3. FunctionInvokingChatClient automatically picks up the new tools on the next iteration of its loop

Prerequisites

• .NET 10 SDK or later
• Azure OpenAI service endpoint and deployment configured
• Azure CLI installed and authenticated (for Azure credential authentication)
• User has the Cognitive Services OpenAI Contributor role for the Azure OpenAI resource

Running the sample

Set the required environment variables:

$env:AZURE_OPENAI_ENDPOINT="https://your-resource.openai.azure.com/"
$env:AZURE_OPENAI_DEPLOYMENT_NAME="gpt-5.4-mini"  # Optional, defaults to gpt-5.4-mini

Run the sample:

dotnet run