Guild Description/MotD limits
 

Does anyone know what the character limit on the guild description and MotD is?

Answer : It's hard to say because depends on the type of characters and the colour markdown counts as well.
I would say between 1000 and 1500 character for each.

If you want to change them via addons keep in mind that changing guild related texts too often (more than 1 change within 2 seconds e.g. at guild notes so similar could count for motd and description too) will get you kicked for message server rate spamming, most probably!
So creating addons which will write and read them several times in a short timeframe will most likely not work as you get kicked.
You'd have to try this.

Thank you very much

Understood. Only plan on doing once on add-on startup for the most part, as a current plan, but regardless, no where near that often, but thanks for the heads up!