Family Tree Research Skill
I'd had the idea myself long before, but never got around to creating a skill for it. I gave AI an export from MyHeritage and asked it to suggest where to look to expand my family tree... and we did make some progress. But it was pretty tedious and slow.
Then I came across an article on Lupa.cz linking to this repository containing a skill for Claude.

I gave it the same source materials, and before half the country caught on to the same idea, it worked really well — there weren't so many restrictions on automated record access and similar things.
I'm currently at ten generations and over 130 ancestors. I've hit a dead end in one branch and am waiting for responses from abroad.
Otherwise, it's the ultimate genealogy assistant. It searches records, verifies findings, suggests next steps, and as a bonus, it can even build you a website presenting all your family tree data, along with interesting discoveries, in a clear and organized way.