api-shape-explorer

Generate multiple radically different interface designs in parallel rather than committing to your first idea. Assign each design a distinct constraint, such as minimizing method count or maximizing flexibility, then compare them on simplicity, depth, and ease of correct use.

Design It Twice comes from "A Philosophy of Software Design" and states that your first design idea is unlikely to be the best. The approach requires producing several contrasting designs and comparing their trade-offs before choosing one.

Each sub-agent receives the same module requirements but a different design constraint, such as minimizing methods, maximizing flexibility, or optimizing the common case. This forces genuinely divergent outputs rather than minor variations of one idea.

No, the Skill is purely about interface shape and explicitly avoids implementation. It produces interface signatures, usage examples, and trade-off comparisons so you can choose a design before writing code.

Skip it for trivial modules with obvious shapes or when an existing pattern in the codebase must be followed for consistency. The comparison overhead is most valuable for modules with significant hidden complexity or unclear caller requirements.