You describe your characters with the intention of painting their portrait on the canvas of the readers' minds. The descriptions are either detailed or vague depending on the amount you wish to rely on your audiences' imagination/participation. In both cases you, yourself probably have a very specific idea of your characters' physical description, and may even have based them on someone you know or have seen. You will never know what your words conjure in the minds of diverse others. But you can get close through the facility of AI imaging. Simply input the description you used in your book and press the 'generate' button, and presto!
Here is the description of Isaac Amsalem, from my book 1634: the search for El dorado. And it is frighteningly close to how I envisaged him. If a simple AI app sees Captain Isaac like this, perhaps the rest of the world does too.
40-year-old Caucasian man with brown eyes, high cheekbones, straight nose, full lips, long black curly hair, dark eyebrows, full beard, and long-shaped face, extremely handsome, scowling, weatherbeaten skin tone, pirate costume, ultra-detailed