I would have the top level tag "Rulebook" and put "Core Rulebook" as a sub-tag. Under Rulebook also have "Player Handbook", "GM handbook" and "Splatbook". Keep the rules together.
Also tags for your dominant systems (ex DnD, PbtA) including "System Agnostic". Perhaps add subtags "Pre-made" and "Generators" under "Setting". Publisher tags? Language? Decade/year of release? Have played?