Building a tool doesn't automatically solve the return-visit problem. Plenty of tools get used exactly once, out of curiosity, and never opened again, which puts them right back where a single piece of content started.
The tools that actually get reused share a few specific traits. None of them are complicated to build. Most of them just get skipped because they're easy to overlook.
The output is personalized, not generic
A tool that gives everyone the same result regardless of their input isn't really a tool, it's content wearing an interface. The ones people come back to take real inputs and produce an answer specific enough that it couldn't have just been a blog post.
There's a reason to check it more than once
Tools that reflect something that changes over time, a score, a status, a recommendation, give people a reason to return on their own schedule, not just when you remind them. A one-and-done calculation doesn't have that pull.
It takes less effort than the thing it replaces
If your tool takes longer to use than the manual version of the same task, it won't survive contact with a busy person. The tools people rely on save real time or real thinking, not just make the same process feel slightly more official.
"A tool that gives everyone the same output is content wearing an interface."
None of this requires complex engineering. It requires designing for a second visit from the start, instead of treating the first visit as the finish line.