Which Mods Need It in Curios API

Install Curios API whenever a mod lists it as a required dependency, or when a mod offers optional integration you want to enable. If a required dependency is missing, the game reports a missing-dependency error for the mod id curios.

• Many equipment and accessory mods (rings, amulets, charms, backpacks, artifacts) build their wearable slots on Curios API.
• Some mods use it optionally: with Curios API installed they unlock extra accessory slots - for example, Ice and Fire can use it to enable a dragon-charm accessory slot.
• Modpacks frequently include it as shared infrastructure for several accessory mods at once.

Rule of thumb: add Curios API when a mod tells you to (or when you want a mod's optional accessory slots), and leave it out otherwise.