The Foolish descriptor on p. 73 of the Cypher System Rulebook seems to be intended for playing characters who are idiots. A character with this descriptor has -4 to their Intellect pool, and all expenditures from that pool have +1 to their cost. They also have +1 to the difficulty of some kinds of task: Intellect defence tasks, and rolls to spot illusions, disguises and traps. That increased difficulty adds +3 to their d20 target numbers for those tasks.
The benefit of being Foolish is that you get to roll twice for all tasks and take the higher roll. And that's huge. It raises your average roll by just over three, negating the increased difficulties, and making all other tasks much easier. Your chance of rolling a 1 drops from 5% to 0.25%, and your chance of rolling a 20 rises from 5% to 9.25%. Here's an Anydice program you can use to look at the statistics. I haven't found any other descriptors or foci in the rules that have this benefit: it seems to be unique to Foolish.
This looks overly advantageous for any character who isn't based on spending Intellect points. Have I missed something in the rules?