The line is not a description
Most people think the line (the tagline, the one-liner, the answer to “what do you do”) is a description of the thing. So they write what the thing IS: features, categories, comparisons. And it never lands, because a description can be true and still tell a stranger nothing about themselves.
The line that works does one job: it makes the right person recognize themselves.
So it isn't really about your thing. It's about the moment your person is in when they need it. What are they leaving? What are they afraid of? What have they already tried that didn't work?
A test I use: cover the name. If the line could belong to three competitors, it's a description. If it could only belong to you, it's a line.
Worked once, on a coffee roaster nobody had heard of:
Description: “Specialty coffee roasted in small batches.” Line: “For the people who moved to the neighborhood before the good coffee did.”
Same beans. One of them is a stranger's Tuesday. The other is a label.
That's the whole craft. The rest is finding the exact words, which is slower than it sounds.
The desk note above says how to get yours. First line free.