01 Write the brief before the prompt
How I ran six design agents on one site without them drifting.
When I wanted new directions for gantry.world, I didn't prompt one agent six times. I wrote one brief and gave it to six agents at once.
The brief had three parts:
- Constraints. Colours only from one fixed set. Pages that open straight from a folder, no server needed. Mobile first, because most visitors arrive on a phone.
- Facts that can't change. What the site offers, the prices, the real catalogue, and the lines I never want to see. Agents don't drift on facts you name.
- What "done" means. These two pages, these six screenshots, these checks. "Take a screenshot at phone width and look at it" catches more than "make it responsive".
Everything else was theirs to decide. Six very different designs came back, and I judged them side by side from screenshots on one page. I picked my two favourites and had another agent merge them.
Try it: before your next big request, write the facts, the constraints and what done means. Then prompt.