How do you make a tool that doesn't break any block faster/doesn't have a specific function?

I want to be able to create a weapon which has the fastest possible attack speed and isn't effective at breaking any block in particular more than your bare fists, and also doesn't do specific things like till dirt, strip logs, or have the swipe like a sword.
It has to be a tool rather than a regular item because I need to be able to put in the attack speed.
Special and multitools just give me errors because I presume there's someplace you need to like add code to it, and I have no clue where that place is or how to code.