Back to the Spencer tool. I've read a tad on the subject, but not enough to be dangerous. One does wonder why one would go to the trouble of manufacturing two concurrent tools (rifle/carbine) to service the same take-down functions. And, if so, why have rifle tools survived in abundance when alleged carbine tools (servicing many times the number of carbines manufactures) have not? Could the "carbine" tool variant tool be a post war modification of the wartime "rifle" tool, as was done with some Sharps and musket tools?
My carbine is an early 1863 delivery, so I'll run on the proposition that rifle tools, if rifle tools they be, were issued-out at least with these early carbines. Certainly the fitted screwdriver blades are a ready help.
And, as to that pesky hole. I can't recollect any of the myriad of other CW era gun tools having one. Spencer boxes, at least through some of the Blakeslees, all had impliment pouches, and it's just hard to envision cavalrymen clanking around with gun tools dangling about their persons from lanyards. Is there anything in Spencer assembly or disassembly that the hole would aid?