Is it possible to add new options to Writing Tools?

My favourite thesaurus of choice is Wordhippo.com but it isn’t listed under Writing Tools alongside thesaurus.com etc.

I’ve had a look around but can’t see a way of adding custom tools - is it even possible? The URL would have to be something like:

https://www.wordhippo.com/what-is/another-word-for/<$selectedword>.html

I came here for this exactly! This would help non-English authors a lot, I think.