Final answer:
Informing your school about your employment is crucial as they can provide endorsements and references that reflect your credentials and personal attributes, such as work ethic, which is particularly important in markets with asymmetric information.
Step-by-step explanation:
The most important reason for letting your school know when you are hired for a job is to leverage the school's network and reputation to gain additional credibility in the labor market. Schools often serve as a pre-screening mechanism for employers, looking at factors such as degrees, awards, and grade point average to assess a candidate's potential. By informing your school about your employment, you can ensure they are able to provide accurate references to employers who value not only your education credentials but also insights into personal attributes such as work ethic and energy level.