02.3-function-calling

Chapter 2.3 -- Function Calling Walkthrough

Companion code for Generative AI in .NET, Chapter 2 section 2.3.6 ("A Weather + Calendar Assistant with Three Tools").

Wires three plain-old C# methods (GetWeather, ListEvents, SendReminder) into an IChatClient via UseFunctionInvocation() and lets the model choose which to call to satisfy a multi-part user request.

Run it

export OPENAI_API_KEY=sk-...
dotnet run --project samples/ch02-extensions-ai/02.3-function-calling

What it shows

• Building tools from local methods with AIFunctionFactory.Create(...).
• Composing the function-invocation middleware with ChatClientBuilder.UseFunctionInvocation().
• A single user prompt that triggers parallel tool calls -- weather, calendar, and reminder.

Manuscript reference

• Manuscript/Chapter-02.md, sections 2.3.1 -- 2.3.6.
• Figure 2.4 ("The Function Calling Sequence") and 2.5 ("Multi-Tool Orchestration Flow").

Prerequisites

• .NET 9 SDK and an OpenAI API key.