History. Your knowledge of traps grants you insight when answering questions about locations that are renowned for their traps.
Investigation and Perception. You gain additional insight when looking for traps, because you have learned a variety of common signs that betray their presence.
Set a Trap. Just as you can disable traps, you can also set them. As part of a short rest, you can create a trap using items you have on hand. The total of your check becomes the DC for someone else's attempt to discover or disable the trap. The trap deals damage appropriate to the materials used in crafting it (such as poison or a weapon) or damage equal to half the total of your check, whichever the DM deems appropriate.
Additional uses. You can use your thieves' tools to do a variety of things, as your DM if you may use the tools for a specific task. Examples of such tasks are as follows; Pick a lock, disable a trap.