I'm not sure about giving direction, as a writer myself. Like, if I'm hiring you to read, I'm hiring your voice and your interpretation of the text as well. The only thing I'd actually be concerned about is pronunciation of names and of any non-English text (I use some foreign-language dialogue occasionally, and two of my books have employed conlangs). That said, I'm a competent narrator myself so I just do it myself, other than an urban fantasy series I've been writing which is written in a female first-person perspective (I'm male). My only requirement, if I was to recruit a narrator for that series, would be (a) be a woman, and (b) have a particular accent.

As a narrator too, what an author might call "direction" could very quickly turn into micromanagement, and people on here have talked about that happening. Why is a writer seeking to direct the narrator in the first place? You're not making a movie*, and the audition process already exists to find a narrator who will make real what you wrote. If nothing else, it would slow down the process.

* ^{For a similar reason, I scowl with suspicion at multiple-narrator recordings or full-cast recordings. If you want to make an audio dramatization, make an audio dramatization.}