These well-worn boots have an ever-changing arcane circle ingrained into their heels. While wearing the boots, you can use an action to speak their first command word to create an arcane circle, as per the "teleportation circle" spell, on the ground below you. The circle appears as a trail of dirt or similar muck from the bottom of the shoe, and is treated as a permanent one for the purposes of this spell. Speaking the first command word again destroys the first circle, magically cleaning the surface it was placed on, before creating a new one at your location.
You can speak the boots’ second command word as an action while wearing them to cast the "teleportation circle" spell, except that this circle is only 5 feet in diameter. This circle’s sigil sequence matches the one created by the first command word and links to its location. When it’s created, the circle appears under your feet, centered on your location, and you immediately teleport through it. Only a circle created in this way can connect to the permanent one created by the boots’ first command word. If the permanent circle is washed away or otherwise cleaned or destroyed before you speak the second command word, the spell fails and the circle isn’t created.
Once you use the boots to teleport in this way, they can’t do so again until 1d3 days have passed. In the meantime, you can still speak the boots’ first command word.