The description of the Robe of Useful Items (BR 195) states that the wearer can detach a patch causing it to become the object or creature it represents.
Does the wearer know which patch contains what object or creature?
The description of the Robe of Useful Items (BR 195) states that the wearer can detach a patch causing it to become the object or creature it represents.
Does the wearer know which patch contains what object or creature?
The Robe of Useful Items states (my emphasis):
While wearing the robe, you can use an action to detach one of the patches, causing it to become the object or creature it represents.
This implies that there is a visual representation of the item on the patch - making it clear what the item is to anyone that can see it.
This is also supported by the picture in the DMG: