My recommendation would be to keep them as simple and to the point as possible. Several bullet points about each general type of job, examples being Shipping and Receiving, Batch Making, Sanitation Department Employees, etc.
I would highly recommend, however, that everyone's Job Description include a bullet point that state that it's their responsibility to ensure that they will continually strive to do their part to endure that only safe, quality food that meets all applicable regulatory and industry standards and requirements is shipped out the facility doors. Food safety and quality is the responsibility of everyone at your facility, top to bottom of the totem pole.