There's been a recent spate of queries from writers who don't want me to know who they are. (Sadly, none of them appeared to be from Idris Elba or Simon Baker.)
This is an almost instant pass for me (I'm not sure about other agents, you'll have to ask them.)
I'm all for discretion and certainly willing to have you query under a nom de plume, but not attaching your name or any name to a query just seems like starting off on the wrong foot.
I've also had people write to me and say I have to sign a non-disclosure agreement to read their query.
Well, no, no thanks.
If you're absolutely determined that your identity must be a secret or you want someone to sign an NDA you're better off hiring a publishing attorney who also makes deals. They're out there, you just need to find them.
I can't help you if you're hiding.