Minecraft wiki entry for Mule, associated text: Equipment can be placed on a mule by holding it and then right-clicking on the mule, or by accessing its inventory. A mule's inventory can be accessed by mounting the mule and opening the player inventory or by sneaking and then right-clicking on the mule. A mule starts out with just a saddle slot, but if it is given a chest, it acquires 15 more inventory slots that can hold anything the player wishes.