Close your eyes and imagine the company (department) exactly the way you would want it.
How would it operate?
Think about the details and write them down.
What is the passion be behind why you do what you do? What keeps you motivated to go to work in the morning and what makes you feel accomplished when you lay your head down at night. Write down what comes to mind.
There is no reason the things that you write down should not be what you do daily. If there are things that you would like to be able to do more of, be sure to include them in your description.
Include company (department) culture in your description. How would you like to feel about coming to work every day?