The ツルハシ、オノ、クワ、and ジョウロ can all be upgraded 4 times. It takes 2 days to upgrade a tool. While クリント is upgrading a tool、he will be unable to do anything else. クリント works on festival days、though save for two exceptions you cannot drop off or pick up tools on festival days. The two festival days that you ''can'' drop off and pick up tool upgrades on are the Dance of the Moonlight Jellies in the Summer、and スピリットイブ festival in the Fall. If you drop a tool off the day before a festival it will be ready the day after the festival.