Okay, I used the Omni-Tool in the demo and it was totally swell... so either the demo had no requirements for using it or I wasn't even aware I fulfilled any requirements.
I didn't get the impression at all that the Omni-Tool required any skills to use it. I assume that the associated skill is lockpicking, because my hacking/mechanical skills are quite high.
I would appreciate it if the info in the Omni-Tool description was changed so that it states that it's actually a skill-associated tool. Thanks.