A cover letter that summarises the resume has wasted a page, because the resume already summarises the resume. Build this one move by move — salutation, opening, two evidence paragraphs, the transition, the fit, the close. Then run the swap test: paste a competitor's name over the employer's and see how much of your letter survives unchanged. Everything that survives is a form.
Build the letter
Target 250–400 words, three or four paragraphs, one page, never more.
The letter, live
Every choice on the left rewrites this. Word count and specificity update as you go.