Most of the cast lists I've seen are useless. They seem to fall into one of several categories:
Description – tells you hair and eye color, height and weight, build, etc. For women, there are their measurements and bra cup size; sometimes states appearance based on (real person). May tell you what abilities they have: physical strength, paranormal powers, wizard, etc.
Relationship – tells you who their ancestors, family, or friends are: grandparents, parents, brothers, sisters aunts, uncles, cousins, etc.
Plot – tells you the point in the story's chapters or plot line in which the character was introduced. May mention what part the character plays in the plot at that point, and if so, their involvement is not updated as the plot evolves.
Of the above, Plot is probably the most useful. However, it is just a prompt to the reader so they can recall the character's initial involvement in the story. In long stories, it may be helpful to some readers.
The author has a choice: list all characters or only the main characters. I keep a character list for my reference, but I do not post it. I think I'm over halfway complete with writing Part 2 of The Ark. My character list has over 250 characters identified by name in the story. Most of those are bit players that are mentioned (e.g., "Take Bob Johnson with you.") and used to support the main and major supporting characters.
Listing just the key characters with a brief description would require about 3-4 printed pages. Listing the entire cast with a detailed description of their primary involvement would require 20+ printed pages.
In the first case, telling someone that Ensign Kenneth Bilart is the officer in charge of Division 2, Seal Team 2, Troop 1 identifies his position, but failure to define his involvement in the plot makes the prompt almost useless. There would also be no prompt for the names of bit players that are periodically mentioned in the story
In the second case, posting the entire character list with a description of plot involvement of all named characters would be difficult and time consuming to maintain in a meaningful way and the cast list would be filled with spoilers.