I built my first AI agent. It was mostly plumbing

I spent a weekend trying to understand how AI agents actually work. Not the pitch deck version. The code version. What does function calling look like in practice? What happens when two agents are chained together and one of them fails? I built a multi-agent research assistant in TypeScript to find out. Three agents: an orchestrator, a summarizer, and a writer. Each one does one job and hands off to the next. Running a model locally is weirder than it sounds. I used Ollama, which runs the model directly on your machine. No API key, no remote server. The first time my Express app got a real response back from localhost, I sat there for a second. It’s just an HTTP call. Your code genuinely cannot tell whether there’s a llama3.2 process on your laptop behind it or a data centre somewhere. Nobody told me that LLMs are just APIs. Text in, text out. Everything interesting happens inside that call, invisible to your code. Function calling is less magic than I expected, which was both a relief