Support letter from my therapist

I have a psyche evaluation already from the mental health person in my surgeon's office which should be enough for insurance, but I am wanting to make sure I cover this requirement without any questions. I asked my therapist who has seen me for several years to write up some kind of letter stating that I am a good candidate for WLS. She is the one who first brought up WLS as something for me to consider. She is only too happy to do it but would like to know what kinds of things she should include in the letter. Does anyone have ideas of what should be included? Anyone have a sample letter example from your therapists? I tried searching on this site but couldn't seem to find anything about this topic.

My program had my therapist write a letter that said I'd seen her for x amount of sessions and that I'd been actively engaged in the therapy process. It stated that she felt I was a good candidate for surgery and had been encouraged to return to therapy after surgery as needed. I have a significant mental health disease and that I had that letter combined with a letter of support from my psychiatrist stating that I was stable and compliant with treatment. My insurance company didn't question my psych clearance with those letters.