A story card is a fact you pin down so the AI can't quietly rewrite it later — a character's motive, a kingdom's border, the thing that happened three sessions ago that everything since has hinged on. You don't need many. Most long-running worlds we've looked at hold together on five or six well-written cards, not fifty vague ones.
The best cards are specific and load-bearing. "The captain is loyal" is weak — loyal to what, under what pressure? "The captain took the crown's coin twice and hates herself for both times" gives the storyteller something to actually write from, and it'll surface that tension in scenes you didn't plan for.
Write cards for things that would be expensive to get wrong, not things that are merely true. You don't need a card for the color of a tavern's door. You do need one for a betrayal, a death the story shouldn't walk back, or a rule about how magic works in your world that a generic fantasy story would otherwise default to.
Cards compete for space in the context window along with your recent turns, so a card that's vague enough to apply to everything ends up influencing nothing. Rewrite it until it's specific enough that only one scene could have produced it.
Revisit your cards every so often, especially after a big turn. A card written for where the story was twenty scenes ago can start working against where it is now — update it instead of adding a second, contradictory card on top.
