The pages are the agent

The sentence was cheap because the pages were expensive.

This week Paul is teaching a course. Business students will build AI agents for a gym: one that finds members who stopped coming, one that writes emails to bring them back, one that handles replies, one that updates the database.

The first thing students ask is the basic one. How do you actually create an agent? Is it as simple as asking Claude to build one? Paul wanted to answer that with a real run in front of them, not a slide.

So he ran it. Fresh folder, one sentence: build me an agent that finds the gym members who have stopped coming and emails them. Twenty one minutes later all four agents existed and had written to the same sixty five members.

That sounds like a magic trick. It is not. The folder was not empty.

Inside it were three role pages, one per agent, saying who each one is and what it does. A runbook listing what happens in what order. An email rules file saying what the emails sound like, what they never say, how long they are. Sample data. A reply handling guide. All written before the sentence was typed.

The sentence cost twenty one minutes. The pages cost days. And the pages are the agent. Without them, the same sentence would have built something, but not something that worked the way this one did. The rules would have been guessed. The handoffs would have been wrong. The tone would have been generic.

This is the part that disappears in the story people tell about AI. You ask and it builds. But what decides whether the thing it builds is any good is not the asking. It is everything you put in place before you ask.

Here is the rule that came out of it: before you start typing, write down who this agent is, what it does, what it never does, and how it talks. If you cannot write that page, you are not ready to build.

Lena