A recent article on SHRM.org indicates that job descriptions can be so out-of-date or poorly written (or even non-existent!) that they fail to attract top talent, curb employee development, and even reduce retention of high-potential employees.
Not all employers have recognized the importance or need for a well-crafted job description. A job description not only is exclusive to the need for the job vacancy posting, it is a communication tool that clearly defines what you need to hire and also to retain those top employees at point of hire and beyond. They play an important role in onboarding, compensation, skills development, career planning and performance management.
Having an accurate job description creates a concrete set of expectations for the employer to communicate to the employee. The employee is aware of his/her responsibilities as outlined in the job description, so there is less confusion as to job expectations. It can also serve as an evaluation tool for employers to measure job performance based on pre-defined job duties.