As a ninja I often bump into these 2 scenarios:

1. Ran out of shihei in the middle of the fight -> frantically trying to rummage through my sack to get a toolbag over to my main inventory and pop it. (typically happens after a big TP move or ga spell, when i need it most @_@)

2. Not knowing I've ran out of shihei and been using the universal tool without knowing, which typically cost x2 the price if i buy from npc. Used it all up on utsusemi and cannot cast miwagari/kakka etc.

My suggestion is to have a command, similar to /recast, where it will reveal the number of queried item you have in your inventory, for e.g:

> /checkStock "Shihei"
< Shihei : 75

This will be very useful to add on a utsusemi macro, then a ninja or /nin will know whether he/she is low on shihei and can pop a toolbag in a less "exciting time" than in the danger of death

Can also see this being useful for any range attack user, keeping track of ammo