If you are building agents, the most important decision you make is where to put the work that keeps the agent safe. Most of it goes into the agent — better prompts, more rules, tighter tool lists, careful output filters. That approach works. But there is a different approach that produces stronger results with less ongoing effort, and it starts from a different idea about what keeps an agent safe in the first place. Let me start with a toy. The Shape Sorter A toddler gets a shape sorter. A board with holes. Square block, round block, triangle block. Nobody explains the rules. The toddler tries the square in the round hole. It doesn't fit. They rotate it. Still no. They try the next hole. Click. The toddler learned the rules by running into them. The toy didn't lecture. It just refused. This is how agents should be kept safe. And how they should be built. Where the Work Usually Goes The default approach is to make the agent itself safe. Pick a model. Write a long prompt full of rules. Don't delete files.…