Grammatically Correct: The writer's essential guide to punctuation ...

GRAMMATICALLY CORRECT
PUT A COMMA BETWEEN TWO ADJECTIVES THAT PRECEDE A
NOUN, PROVIDED THOSE ADJECTIVES ARE OF EQUAL WEIGHT
In most cases, commas are needed only when you have at least
three items in a series: You wouldn't use them for just two. For
example, you wouldn't put a comma in Arnold crafted his reply
slowly and meticulously or Teachers need hours outside of class
time to plan new curricula and meet with parents. You do,
however, need to separate two items when those items are adjectives
modifying a noun.
Her bold, innovative rhythms had the audience swaying to the beat.
The relaxed, laid-back atmosphere was a pleasant change.
The door opened with a grating, creaking sound.
A grumpy, tired-looking waiter took our order.
This rule holds only if the adjectives are of equal weight, meaning
that they both modify the noun equally. To determine whether
they do, use this test: Would the sentence still "sound right" if you
reversed the adjectives, or if you put the word and between them?
For example, you could say innovative, bold rhythms or bold and
innovative rhythms; a tired-looking, grumpy waiter or a grumpy
and tired-looking waiter.
In contrast, consider the adjectives in the following sentences:
He went in for a routine physical checkup.
A purple-clad French skater was next on the ice.
In my opinion, he's a long-winded, pretentious, pompous old bore.
You wouldn't say a physical routine checkup or a routine and
physical checkup; a French purple-clad skater or a purple-clad
and French skater; an old pompous bore or a pompous and old
bore. In all these cases, the second adjective effectively forms a unit
with the noun: a physical checkup, a French skater, an old bore.
Accordingly, the adjective that precedes this unit is treated as if it
were the only one: that is, no comma. (In the last example, the first
two adjectives, of course, take commas because of the three-ormore
rule.)
Also, do not include a comma between two adjectives if the first
adjective is modifying not the noun but the other adjective. For
example:
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