Agent Foundations

What an agent actually is, how the loop works, and when not to build one

• What Is an Agent? The Loop That Changes Everything — The one-line definition that actually works — an LLM given tools, run in a loop, with a stopping condition — and the single property that separates agents from chatbots, workflows, and scripts: the model directs the control flow. (5 lessons, 45 min)
• The Words People Use — Agent, Agentic, Copilot, Assistant — Ten words for overlapping things — agent, agentic AI, copilot, assistant, chatbot, workflow, RPA, orchestration, autonomous, AI employee — used inconsistently by vendors, analysts and bloggers. Rather than a private taxonomy you will be talked out of, this module hands you one disambiguating question that works whatever the vocabulary: which decisions does the model make at runtime, and which are fixed in code? (4 lessons, 35 min)
• The Agent Loop: One Turn at a Time — The loop, slowed down to its unit of work: what happens inside one turn, a real three-turn transcript, the five stopping conditions that keep loops from running forever, and the anatomy of a tool call — including why its result becomes the next turn’s input. (5 lessons, 40 min)
• LLM Mechanics for Agent Builders — No Math Required — The five facts about how LLMs actually work that every agent engineer runs into within a week: tokens are the meter, the context window is the whole world, the model remembers nothing between calls, temperature 0 is not determinism, and non-determinism compounds until testing becomes statistics. (5 lessons, 45 min)
• Tools and Tool Use: The Contract Between Model and World — What a tool looks like from the model’s side of the glass, why the name–description–schema contract is the only documentation the model ever reads, and how tool and result design decide whether your agent works. (5 lessons, 45 min)
• Agent Memory: Remembering and Forgetting on Purpose — Why LLMs forget everything, the three horizons of agent memory, files as the simplest honest store, the ways memory becomes a bug — stale facts, poisoning, privacy — and why forgetting is a feature. (5 lessons, 40 min)
• When NOT to Build an Agent — The restraint module. Most problems labeled “agent” are scripts or workflows in disguise — this module gives you the decision table, the honest cost accounting, and the anti-checklist to say so before the budget is spent. (4 lessons, 35 min)
• Anatomy of a Real Agent: One Run, Every Part Named — Read one complete support-agent run end to end — setup, six turns, one tool error, one recovery, a clean stop — and learn to name every part: the trace, the logs, the evals, and where the risks lived. (5 lessons, 45 min)