"I have many warm-hearted friends."
Grammatically, you can check the Speedy Guide 5.(1) and 2.(4) and think about it.
Separately, personally I am more used to describing behaviours rather than people with 热情; If I do, it would be preferably in the predicate form rather than attributive form, because of their behaviours at that moment.
Also the meaning of 热情 is not "warm-hearted" to me. People that talk to me when I'm down, send cards and flowers to me when I'm in hospital are warm-hearted but that's 亲切 not 热情. A hospitable host that always accompanies the guests, arranges lots of activities, parties, gatherings, dinners is 热情; An audience of a pop concert that screams, yells and claps hands vigorously is 热情.
It's right sentence. But used in different circumstances.
When you say this one, always there's some following sentence.
For example: 我熱情朋友很多，他們會幫我。 I have many enthusiastic friend and they will help me.