functionary
A worker who mainly follows official rules and procedures.
A functionary is someone who holds an official position where their main job is to follow rules and procedures rather than make big decisions. For example, a person who stamps forms or checks that paperwork is filled out correctly is a functionary.
The word sometimes suggests someone who focuses so much on following rules that they forget to be helpful. If a functionary at the library won't let you borrow a book because you're one day late returning another one, they might be thinking more about the rules than about actually helping you.
Every organization needs people to handle routine tasks, but when someone acts like a functionary, it can mean they've stopped asking whether the rules make sense in each situation.