Prospective clients often bring me cover letters that are thicker and longer than their resumes. I ask: If a hiring manager doesn’t want to read a long resume, why do they want to read a longer cover letter?
My philosophy is simple. Keep your cover letter concise and focused on your strongest qualities. State your current duties in a sentence. Sprinkle in a few of the soft skills that employers ask for in job postings. Don’t repeat specific details that will be played out in the resume. Use the cover letter to drive the employer to the resume. Keep it short and focused on the most important qualities you will bring to a new employer.
P.S. There is one exception to what is said above. Some employers, very few, give specific instructions about what they want in a letter. In those rare cases, be sure to address what the employer is looking for.