In my experience with job applications when applying for jobs there is a huge range in the types of job descriptions. In some cases, companies are vague, leaving me to wonder if that is all the expectations or requirements for the position. In other cases, the descriptions are long and detailed. In my opinion and personal experience this puts both the company and the applicants at a disadvantage. It has been frustrating when applying for a job with a short description, feeling like you fit the company’s needs well, but then don’t get an interview. With longer descriptions, it makes it more difficult to feel qualified to apply or overwhelmed by all that the job would entail. This affects companies as well, if the job description is short and vague, the number of applicants they get will increase. In turn this will lead to more applications that have to be gone over and having more applicants that do not fit what the company is looking for. A longer description can lead to more specialized applicants but could also cause the company to lose applicants due to them being turned away by the long job description.
Thinking of my own position, when I look at a similar position posted by the company, I work for it does not fully encompass the work that I do. I think it is reasonable to expect that not all aspects of the job are reflected in the description of the position. I would assume that most people would feel that they do more than what is in their job description.