You can never rely on an agreeable person to complete a task set by you. They don’t have the capacity to say no, so you think they’ll do anything. Wrong. 90% of the time, they’r doing the things they hate. They’ll say yes, but completely flop the task.
Disagreeable people seem to be the opposite. They’ll say no a lot of the times, and you can’t really command them. Even the lazy ones. But when they say yes, they do it near 100% completion.
The more someone says no, the more likely they will complete a task they say yes to. A law that’s to be held loosely. More true in the workplace. Another factor is holding something over them as pressure to complete the task. “You said no to that, now complete this”.