Andy Kear (from Clockwork Creative Technology, with a companion skill for script XML) is a more sophisticated skill, and it’s worth studying closely because it argues this very thesis in its own README — that there should be a clear boundary between what the AI determines (the layout logic and content) and what must be deterministic (the XML structure). It supplies that deterministic layer as a specification: all 18 layout object types, the decoded flag bits, the element-ordering constraints, and the paste-handler rules that cause FileMaker to silently drop malformed objects. And it was built the hard way — not from documentation, because Claris publishes no formal spec for the clipboard or FMUT XML formats, but by empirical round-trip reverse-engineering (generate, paste, save, copy back out, diff against native) across more than thirty-five production layouts. It is genuinely excellent work. It is also the clearest illustration of a skill’s ceiling: it makes the shape known to the model, but the model still authors the XML. A perfect spec lowers the error rate dramatically; it cannot make a wrong shape impossible, because the model is still doing the typing. Kear names precisely the boundary that the next rung up enforces in code rather than describes in prose.

Claris FileMaker Pro Skill is a skill in the pure sense, and a good one. It ships reference catalogs — all 360 calculation functions, all 155 script steps, the error codes, the help-center URLs — with a local-first, live-verify strategy and even a version-drift detector that flags when a fetched doc references a newer FileMaker version than the skill was built against. What it fixes is what the model knows: it stops your model from hallucinating a function signature or inventing an error code. That is real value. But it is, by design, a knowledge layer. The model still authors the XML; the skill just makes sure the model is better informed while it does that.