Skill proficiency affects the amount of energy required to use specific tools. As proficiency increases, energy requirements decrease by 0.1 points [https://gaming.stackexchange.com/questions/258240/what-does-1-proficiency-mean].
The [[Pickaxe]], [[Axe]], [[Hoe]], and [[Watering Can]] use 2 [[energy]]. The [[Fishing Rod]] uses 8 energy. Powering up the watering can increases its cost by 2 energy per level, with a maximum cost of 10 energy using a fully-charged iridium watering can.