use tool when its not equipt and its in your inventory.

[Granger]

On further thought: the current 'setting hand contents aside' for crafting (where stuff in the hands actually isn't unequipped, nevertheless the character magically has empty hands while the crafting is running) could be applied to actions with tools (as long as the tool is in an equipped belt so it can be summoned).

To make this visually appealing (and to add a drawback to the benefit of reduced clicking) animations for setting aside/picking up the hand contents should be added (currently it's instantaneous, which somewhat breaks suspension of disbelief) that add a delay (both at the beginning and end of the action) for characters that don't have the 'really' free hands needed for an action (hand crafting, like shovel/pickaxe/..., would require two empty hands).

This would result in a speed benefit for characters that are actually prepared for an action they are planning to make - while removing the needless risk of RSI caused by inventory juggling required for 'crafting with tool' type actions (chopping trees, sawing boards, digging stuff, ...) - while at the same time retaining the need to actually hold weapons (thus reducing the available inventory size in combat situations).