If I’m going to use tags in my prep its purpose is to let me know how to narrate or act something by giving me some key words (tags) to fall back on.
Let’s say I have a character with the following tags in appearance.
Appearance: Receding thin orange hair, orange mustache and beard, well trimmed and a little curly, and thick hands. Always smiling. A well-worn flat topped sailors hat, dark blue.
Now when I’m narrating him to my players, I’m staring at those tags.
GM: He hugs his well-worn sailors hat, “Well, you aught to know…”
Players: INTERACT WITH HIM.
GM: He smiles and offers the gem. It sits in his open thick hand.
You can do this with more than appearance obviously, and you might not want to overdo appearance like I did in the above example, no need to use a ton of extra narration for no reason. But the point is I would use tags as a way to help my game, as prep, to keep my character consistent, without me having to memorize everything.
They are easy short words or phrases you can just look at and fall back on while delivering the game content.
You can make different categories of tags, or even use them for locations, here are some categorical examples.
Name, race, and appearance, are all words and tags you can look at to use when narrating the actions of the character. Or NPCs appearance on first sight by the players.
Traits are used as tags for how to narrate the character’s actions. What their mannerisms are like. You can also include tactics in personality tags, what kind of approach a character has when trying to get what they want, or when trying to avoid the players, etc
Or just reminders, like ‘affable, reminiscent’. IF you can play off these words. I find it’s easier to word them in a way I can directly use/read.
Ex: Easy to talk to: ‘tell me your troubles’ and Reminiscent: ‘Ah, I remember when…’ and ‘His eyes stare off into the distance, he smiles, paused in memory.)
A long oakwood table: Ink stained. Paper strewn. Cups of quills.
You get the idea. It’s prep stuff, things you can directly use, and so that if the players visit that character sessions later, the character still feels like the same person, because you have all those tags there to guide your narrating.
Added thought just to tie it back to ICRPG:
ICRPG: I think one of the examples given in ICRPG was a word to remind you that a dagger could be used to pry something open, not just stab with. So it would improve your narration by giving you a variety, something you didn’t have to think up on the spot. To help the player come up with ideas of how their prop could be used in a game, with an easy single-word reminder.