3 tools in 1.
To switch using 'auto-switch', just right click on the designated node you want to break, the tool will switch to the correct tool that can mine it the fastest.
You can manually switch via holding the SNEAK (default left shift) while right clicking (on either a node or air) to cycle thru (in the pattern of Axe -> Pickaxe -> Shovel -> Axe).
Please note however, the tool shares it's durability among all 3 states. (As such it comes with a hefty durability)
The tool tries not to interfere with nodes like doors, chests, and other nodes that might have a use on right click (like opening an inventory or formspec)