The documentation of the diagnosis is the responsibility of the provider who is legally responsible for the medical and/or mental health record.
Who can make the diagnosis? That may vary by state, as state scope of practice laws may differ. Medical doctors, which include psychiatrists, can pretty much diagnose mental health and/or personality disorders. Usually Nurse Practitioners and Physicians Assistants can, too. Usually, mental health counselors are able to diagnose.
The Diagnostic and Statistical Manual (DSM) is a specialty book used by mental health professionals. It groups the diagnosis codes by type, such as depression in one category, schizophrenia in another, personality disorders in another. Then, the book lists the symptoms, which may include a length of time, for the different diagnoses. For example, the person may need to have 3 symptoms from section A, one from section B for at least 6 weeks, and one or more from section C.
Just because they say "it sounds like X", it really isn't official until it's formally diagnosed in the medical record. It could be that after further work, the LCSW may have a different diagnosis. There are many that have overlapping symptoms.
If your WH disagrees with the assessment, he can get a second opinion. Just because he doesn't like it doesn't mean he doesn't have it.
BW M 34years, Dday 1: March 2018, Dday 2: August 2019, D final 2/25/21