Letters of intent are similar to cover letter. They require few tricks up your sleeve to get the best out of your writing skills. A letter of intent is intended toward the receiver of your resume. It should give receiver a glimpse of your academic and professional background along with your passion in a particular field of work helps the reader to understand your necessity.
If you are presenting your resume along with a cover letter, chances are that the recruiter would read both of them. The facts to be mentioned on the resume and some extra information like your interests and achievements can be mentioned in the letter of intent to make the reader understand why you are targeting that particular job profile. It is imperative that the employer knows why you are the right person for the job. If you tell them this then half your job is done and it becomes easier for the recruiter to connect with you.