Minecraft wiki entry for inspect, associated text: Specifies the direction of Agent to verify the name of the block.
Must be one of:
forward to inspect the block on the front.
back to inspect the block on the back.
left to inspect the block on the left-hand side.
right to inpect the block on the right-hand side.
up to inspect the block on the top-hand side.
down to inspect the block on the bottom-hand side.