RAG, retrieval-augmented generation, is text our code adds to a prompt before the model sees it. The agent searches the user's notes on every prompt, and puts the closest passages in front of it. The model answers from what the request holds. It still makes every decision: call a tool, or answer. The agent, the loop …

An AI agent is a program that runs a loop around a model. The user types a prompt. The model makes every decision: call a tool, or answer. The agent carries out the decisions, and keeps the conversation. A program around a model is also called its harness. The top bar picks the API: Anthropic Messages or OpenAI Chat …