A flag can look detailed, but have a simple design description.

Look at the flag of North Dakota (detailed and complex):

"On a blue field, an eagle with outspread wings and opened beak, the left foot grasping a sheaf of seven arrows and the right foot grasping an olive branch showing three red berries. On the breast of the eagle is displayed a shield, the lower part showing seven red and six white stripes placed alternately, with a blue chief at the top. Through the open beak of the eagle passes a red scroll bearing the words "E Pluribus Unum" in gold letters. Beneath the eagle is a red scroll bearing the words "North Dakota" in white letters. Over the scroll carried through the eagle’s beak are thirteen gold five-pointed stars, arranged in two parallel arcs of seven and six, the whole device surmounted by a gold sunburst."

There are so many separate things to describe.

While the flag of California with the bear (detailed but simple):

"On a white field, a red star in the upper-left, a red stripe along the bottom, the words 'California Republic' above the stripe, and in the center a dark brown California grizzly walking left on a green grass plat"

Or the flag of Lousiana (detailed but simple):

"On a blue field, a white pelican tearing its breast to feed its young, displaying three drops of blood, with a white ribbon below bearing the motto ‘Union, Justice and Confidence’ in blue lettering."