Why a single resume score is useful
When you're iterating on a resume for a specific role, it helps to have one number you can watch move. This tool is designed around that: you edit your resume, re-run the check, and watch the score change. If adding a section didn't move the number, it probably didn't move the ATS either.
The score here is weighted keyword coverage of the job description — the same signal the first automated filter in most hiring pipelines uses. It is not a human-style grade, but it is a reproducible, honest measurement of how much your resume and the job description overlap in language.