An administrator 's cover letter, as with any cover letter, should emphasize what the person has done for the employer. Do not make the mistake most job hunters make, which is writing their resumes and cover letters so that they just offer a long, boring list of job duties they were required to perform.
Most employers already know what job tasks are performed with specific jobs, and they don't want them restated on a resume or cover letter in any great detail. Instead of listing job duties, focus on what you did for your employer in terms of saving money, increasing efficiency, reducing errors, streamling operations, automating processes, reducing labor costs, etc. Provide any quantitative data that you have.
--Saved employer $250,000 in annual labor costs by streamlining operations
--Reduced error rate by 50 percent saving employer $300,000 annually