The Tool Belt is a nifty mod that condenses your inventory slots for tools into a belt you carry or wear with the Baubles mod. The standard belt adds 2 extra slots that can be triggered by holding down the R key.
But you can add up to 9 slots by combining the belt with belt pouches on an anvil.
And this frees up a ton of space in your inventory bar. If you need to quickly swap tools to the correct one just hold down the R key and swap to what you need!
It can also carry flint & steel and sheers to quickly open a portal or trim your sheep.
And bows and swords are also handy to swap when an enemy in near.