Decisions have two moments: when you make them and when you execute them. Reopening a decided question at execution time is how decisions become undecided again. The discipline is treating the execution moment as implementation, not reconsideration.
Most of what a new tool needs already exists as solved, reusable infrastructure. The skill is recognizing the thin layer that's genuinely yours to build — and refusing to rebuild everything underneath it.
Surveying alternative opportunities rarely produces a better one than the plan you already have. Its real function is to calibrate how much conviction the existing plan deserves.
A focused tool's first job is to find the one use case it handles so well that users can't imagine doing it another way. That use case becomes the center of gravity for everything that follows.