A job description is an internal document that clearly states the essential job requirements, job duties, responsibilities, and skills required to perform a specific role. A more detailed job description will cover how success is measured in the role so it can be used during performance evaluations. They are also known as a job specification, JD, and position description (job PD).
Prepare job summaries, if relevant. You can use the job description template you use for each position that you advertise by filling in the template with the information that is relevant to that position. However, if you do (or expect to do) a lot of hiring of a particular position, you might make a special template that includes a summary of that job. This will save you some time.