Putting Hammered or Crooked on a tool that has the Unbreakable trait makes it take damage when used for the "Hammered" or "Crooked" purpose. For example, a pick with Hammered will take damage on anything hammerable, but not on say, marble, which isn't hammerable. Also, a hatchet with Crooked will not take damage mining wood, but will when breaking leaves, where it wouldn't have taken damage breaking leaves before applying the modifier.
Putting Hammered or Crooked on a tool that has the Unbreakable trait makes it take damage when used for the "Hammered" or "Crooked" purpose. For example, a pick with Hammered will take damage on anything hammerable, but not on say, marble, which isn't hammerable. Also, a hatchet with Crooked will not take damage mining wood, but will when breaking leaves, where it wouldn't have taken damage breaking leaves before applying the modifier.