Show Me What You Got is a Minecraft mod for Fabric. When added to the server, it allows players to display their items in chat by pressing Ctrl+T (or whatever their chat button is bound to) while hovering over an item in their inventory.
The mod needs to be installed on the client and the server in order to function properly.
Clients without the mod can still join modded servers, and also see items shared by others in chat. However they can't share items themselves and also won't see the item's texture in the tooltip.