I've read the Secret History about Tools and you've worried a lot about it and it is not as absurd as it seemed to be. Still, I cannot help but feel that multiplying King's Courts, Platina and City Quarters with it shouldn't be possible. I think it should be:
Tools (Treasure, $4)
Gain a card costing up to $6 that anyone has a copy of in play.
The Plunder card that is most shocking to me, however, is the Nearby trait. A Nearby Peddler looks very awful to play with, as does any cheap Nearby card when Quarry is on the board. A good fix IMO would be:
Nearby (Trait)
The first time you gain a Nearby card in your turn, +1 Buy
(It also kinda weirds me out that the +Buy-on-play trait was considered not interesting enough, but oh well)