Yes, but OpenAPI specs tend to be verbose and hard to navigate. Remembering the exact anchor for the type you defined can be difficult, finding the reference can be harder, and you probably won't get any help from an IDE.
I tend to prefer just writing the yaml, but I can also see why these kinds of tools crop up to mitigate the need to remember all the details.
Yep, it is. Super happy with it. I added some custom themes and links to my second brain, but other than that, all mdBook. I also have more notes about writing a book with Markdown and self-publish at https://www.ssp.sh/brain/create-a-book-on-markdown/.
I tend to prefer just writing the yaml, but I can also see why these kinds of tools crop up to mitigate the need to remember all the details.