Hey Dramasailor, are we using the following XGtE rules about tools and skills combining in this game?
[ +- ] XGtE Chapter 2: Tool Proficiencies
Advantage. If the use of a tool and the use of a skill both apply to a check, and a character is proficient with the tool and the skill, consider allowing the character to make the check with advantage. This simple benefit can go a long way toward encouraging players to pick up tool proficiencies. In the tool descriptions that follow, this benefit is often expressed as additional insight (or something similar), which translates into an increased chance that the check will be a success.
Added Benefit. In addition, consider giving characters who have both a relevant skill and a relevant tool proficiency an added benefit on a successful check. This benefit might be in the form of more detailed information or could simulate the effect of a different sort of successful check. For example, a character proficient with mason’s tools makes a successful Wisdom (Perception) check to find a secret door in a stone wall. Not only does the character notice the door’s presence, but you decide that the tool proficiency entitles the character to an automatic success on an Intelligence (Investigation) check to determine how to open the door.