Evaluating Staff - Job Descriptions Are Too Vague!

Hi All. I am currently evaluating staff performance and found that their job descriptions are too vague for the employees to set feasible objectives for themselves.
Does anyone have an opinion of the best way to tackle this challenge?
Thanks
Sam

Well, the best way you can do is to first judge the candidates work expereince and skills and based on that prepare a job description that marhes to candidate profile and then assign some related tasks or project to them.

Dear Sam,
I suppose you have answered your own question.
If the job descriptions are too vague, who is responsible to change them. This seems to be a poor case gone bad to worse. Look at the situation here. Markets, economies are changing everyday. This in turn changes employees job roles and their productivity too.
If you have not set the right expectations by communicating a change in job role/descriptions, you surely cannot make a comment on their performance.
Regards,
The Training Specialist.

Dear Sam,
In my point of view when a performance management can be successful, when the criteria of the job would be clear for both employee and employer, thus we have the word in performance management (SMART) which clearly mention the criteria when we are setting the objective for the employee. In my point of view for the current stage you can set the objective based on the Key result area of the job scope, and simultaneously start the process of job analysis for your organization.