The idea is simple. A questline for your given tradeskills that upgrades minimum crafting.
Let’s say you start the first quest that unlocks the, “Basic Tool bag,” and you can equip it for +0 to minimum crafting. You then have a questline for every trade skill. Doing a specific tradeskills questline gives +1 to that Tradeskill by acquiring a tool. Then you have another quest to do that isn’t very easy, to acquire another tool that makes it +2.
(Craft a legendary 600 GS item, retrieve blah blah material and craft an apprentice’s tool, then craft 10 more legendary items and retrieve blah blah material and craft a master tool for +2)
Then once you get all the tools to +2, the questline giver gives you a “Master Craftsman Tool bag,” that gives +3 to all Tradeskill crafting minimum.