How are references used by medical schools?

Does anyone know how much admissions use our academic references? Do they have specific criteria they tick them off against, or are they used more generally?

I'm a reapplicant and last year requested to see my reference - it didn't talk about my commitment to the school community or extra curricular hobbies at all, just a paragraph from each teacher about how I did in their subject, and a nice finishing paragraph about how I'd make a great doctor. One of my biology teachers wrote the same for everyone, so according to her my favourite part of biology was ecology.

Should I send an email to my referee asking them to include, e.g. my role as a peer mentor, my work in after school science clubs, tutoring younger students in chemistry etc? Or would it not make much difference?