The purpose of a job description is to persuade, as well as to qualify and disqualify candidates before you spend time interviewing them. If you’re looking for someone with a degree in economics, then putting that on the job requirements list will disqualify the candidates without the necessary qualification. On the other hand, the right copy and tone can help you stand out to incredibly desirable candidates.
Think of this as describing the purpose of the position, and its role within your company or organization as a whole. A job summary will briefly acknowledge the fundamentals of the position, so leave space on your job description template to answer.