> For example, humans usually have a rule that if your teammate hints multiple cards of the same color/number, you should play the newest one. The bot uses a more complicated rule: if the card you just picked up was hinted then play that card, otherwise play the oldest hinted card. That gives you way more flexibility to hint playable cards that would otherwise be tough to get played.

I've definitely seen advanced Hanabi players use a more subtle version of that rule: "If your hint looks like it's telling me to play my leftmost hinted card, how long has that card been playable? If it could have been hinted for play a long time ago, and it's just being hinted now, it must not be playable. So what else must you mean...?"

That version of the rule allows for more subtle cases. Suppose you hint that a player's second-from-the-left and fourth-from-the-left cards are both red. If there hasn't been an opportunity to hint the second-from-the-left since it became playable, go ahead and play the second-from-the-left. If there have been opportunities to hint second-from-the-left, play fourth-from-the-left.

That rule requires human players to model whether the other players' actions in the interim have been "urgent" things that needed taking care of before hinting them, or whether those other players would have hinted them sooner if their card was playable.