Is the toughness of a knowble the exact number of cards you must play or just the minimum cards?

Good catch, it is just the minimum (so equal to or greater than)

The previous version of rules had bullet points that said Jack = 2 or more Items, Queen = 3 or more Items, and King = 4 or more Items. When I condensed that into one bullet point, I forgot to add "or greater than" to the main rule above that bullet point. It has now been fixed to properly say, "To attack a Knowble, you must play a number of Items from your Arsenal equal to or greater than its Toughness."