Should John have proposed the ides of developing job description for the interns?

Application Case “Social Surveyors in flood Hit Areas”.

This case is from the  chapter 4 ( Human Resource Management) text book of Gary Dessler . For your convenience I have attached the case file with this question.

1.Should John have proposed the ides of developing job description for the interns? 

What advantage will the formal JD give?

2. If you were john, how would you have gone about developing the job description?

N.B. : The solution of this case should be big enough for a 25 mins presentation and it should be justified with the HRM theory