In screenwriting you should not have any "chunky" descriptions at all. More than six lines is probably too many; the rule of thumb in screenwriting is that, if you cannot see it, don't write about it. (of course you can see if somebody is shy, haughty, unkempt, doesn't belong where they are, are confused or angry, etc. You might even know their profession, by their costume or makeup).
You should know your characters in great detail, their full biography, economic class, where they grew up, how they did in school and how far they went, WHY they became what they are, and so on.) But that is background work. It doesn't belong in the script. If the actor cannot act it, if the costume and makeup department cannot suggest it, if the sound guy cannot HEAR it, leave it out.
Remember the film is SEEN AND HEARD by the audience, they know nothing about your description and never will. Your character must be revealed through their actions and their dialogue and acted demeanor.
GEOLOGIC RESEARCH LABORATORY
DR. JOHN BROGAN is an unkempt 50 year old man with a receding hairline he does not conceal, with long flyaway brown hair beginning to gray. He is clean shaven and wears a pristine white lab coat that is mis-buttoned. He rises and greets the team with enthusiasm.
Hooray, you're here! I'm John!
This is what you can see. Parts of Brogan's personality are revealed, he is not vain, hygienic but pays little attention to his appearance or dress, and he seems a happy guy without a big ego, glad to see the team and provide some help.
If he is the worlds' premiere expert on mercury inclusions in crystals, that will come out in the questions and dialogue. His credentials, if important, would come out earlier when the team learns of him; somebody else would tell them this is the number one guy in the world.
Describe what you can see, particularly if it reveals character or is important to the story. That can include dress, posture, expression, demeanor, things that can be acted or portrayed in makeup.
Do not "tell" about background, upbringing, what interests them or bores them, when their mother died, or anything you cannot see on the screen. Character is not revealed in exposition in a screenplay, it must be revealed on screen or through dialogue. Anything that cannot be revealed on screen or through dialogue doesn't matter.
If you have a full bio worked up for a character, the actor would probably be interested in that, but it does not belong in the screenplay.