I usually have Shadowheart in my party so I use guidance for basically everything and adding that 1d4 to Astarion's lockpicking check feels honestly gratuitous at this point (I still do it tho)
On the other hand, my Warlock who coincidentally has the best dex in my party, has been burning through Thieves' Tools like there's no tomorrow, since no one has Slight of Hand and I can't be bothered to go back to camp for Astarion unless I'm doing stuff I know involves him. :P I miss Shadowheart having the Urchin background. :P
No but like, sometimes you'll succeed a roll and a message will pop up going "THIEVES' TOOLS USED"
It seems to happen when I roll something that's just a bit more than the DC, so like, a lock that needs 20 and I'll roll 21, it gets consumed. Whereas it seems to happen less when rolling like 10 more than I need.
But then sometimes even this observation doesn't seem to apply.
Are you sure it's actually consuming the tools when you get the message that they were used? I noticed the same message and had the same concern but when I started paying closer attention to the number of tools I had in my inventory it only ever went down if I failed a lockpick. If I lockpick and succeed I get the message, and sure I did use my tools, but they remain in my inventory.
You use thieves tools every time, but they break if you fail. That's the easiest way to think about it. That message popping up doesn't correspond with breaking a thieves tools in my experience. So you get the message, but the total available remains the same.
I know exactly what you mean and it happens to me. Pick a lock and succeed on the first try and get the message it consumed one. Happens randomly for me like you.
I think that's the same message as "used old key". It doesn't get consumed, just informs you how it was solved. But I never paid much attention to it, so I might be wrong.
I've tried to use Thieves tools once and it went like this:
Tried it on a flimsy door, people were looking so I put the tools away. I instead picked up a barrel and threw it at the door at which point i teleport in, met a chick with paralyzed legs and then teleport out. Door was fine though and the thieves tools had done its job.
I can't tell if the game is jank and I'm much too creative or if the game is masterclass and I just can't comprehend its genius.
I was pretty sure that every successful pick needs one tool. Maybe you checked the wrong inventory for how many were used? Party members will just use lockpicking tools from other inventories as well.
Trap disarming seems to only consume the tool if you fail the disarm.
You use thieves tools every time you lockpick, but if you fail they break decreasing your supply by one. If you succeed, you may reuse the same thieves tools for the next lock.
I've noticed this too and have been trying to keep an eye on why. I have noticed that when I have quite a bit of + to the roll (dex, sleight, spell bonuses.) and it's a 10 or below, it doesn't even light up the thieves kit as being used. When it's a higher requirement of 15+ OR I don't use the spell bonus, or I use my main character who has the dex bonus but not the sleight of hand..it doesn't use it on lower requirements. My guess based off this was that if I blew the requirements away (5 or 10 maybe over the requirement?) it wouldn't even bother using one.
It's all conjecture though, but that's the trend I've seen since I started paying attention.