Like, you can consume one to reroll a lockpicking check. That bit makes sense.

But also sometimes you'll pick a lock, not reroll, and it'll consume one of your tools anyway.

Same thing with trap disarming kits.

Do they have a 'durability %' that is just hidden to the player? Does it relate to the difficulty of the lock itself?

Sometimes I'll pick seven doors without a single one being consumed, and sometimes three of them will be consumed in a row.... ?

I don't get it, and I found no explanation for it anywhere in the game.