This will be the book in which your protagonist is introduced, and you want people to hook with her enough to cotinue reading more books later on. You can give loads of information about yet reserve some suprises for later on. I’ll answer your question with a couple of my own:
– Does acquiring the ability deserve a book on its own, or can it be clues that you trickle in now and then?
– What is the central USP: the freelance investigations, or the magic?
– If you say “both” to the USP, will there be enough investigative work in the “acqusition of the ability book” to make it part of the series?
In any account, even if the book is aimed to be part of a series, each must be strong enough to stand alone.
Hope this helps!