The Tool Box can store up to 8 tools in your inventory. With the Tool Box in your hand, right click to automatically store tools, and right click again to release the tools back into your inventory. If your inventory does not have enough slots to restore all of your tools, the extra ones will be dropped on the ground.
(SSP) If a Sickle, Philosopher's Stone, or Water Bucket is in your hotbar, it will be stored by the Tool Box. Opening the Tool Box when one of these items are stored in it will crash your game. When re-entering the game, the tools will be present in your inventory and in the Tool Box.