Most of the time, when you hire people you don’t want to specify exactly what they are to do and how much they would get paid—you don’t want to say if you do X you will get this much, and if you do Y you will get that much. That type of contract is what we call a complete contract. Creating one is basically impossible, especially with higher-level jobs. If you try to do it, you cause “crowding out.” People focus on everything you’ve included and exclude everything else. What’s left out of the contract tends to drop out of their motivation as well.
If you are hiring the right people, you don’t want to include anything too specific in the contract. You want people to buy into the objectives of the company. Be specific about those, and then trust people to quickly understand how they can help maximize the objectives at each point in time. People actually know to a high degree which actions are good for the company and which are not—regardless of what you pay them for.