Personal Utility
Remove friction from one task you already repeat: organize, transform, summarize, calculate, track or prepare something useful.
MVP: “When I provide [input], the app should [one job] and return [useful output] so I can [next action].”
Audience Tool
Give a visitor one clear result: a calculator, generator, quiz, planner, helper or practical resource.
First test: can a first-time visitor understand what to enter, complete the task, understand the result and know what to do next?
GPT / Assistant
Give the assistant one responsibility with explicit sources, rules, output format and boundaries.
Test: one clear request, one ambiguous request, one out-of-scope request and one attempt to make it ignore its rules.
Business / Interactive Product
Prove one user, one core action and one useful outcome before adding accounts, payments, integrations or permissions.
Core flow: USER → TRIGGER → INPUT → CORE ACTION → OUTPUT / CONFIRMATION → NEXT STEP