Twilio: consistent, well-documented, as simple as needed for the problem space but no simpler. As an example of "as simple as possible but no simpler" and also "well-documented", see "What the heck is a segment"[1]. Basically, plain SMS messages can be 160 bytes each, and if you want to send more than that, you have to send a multi-segment message, which sends multiple messages with a common header, which the receiver of the message reassembles into what looks like a single message. If you send a message with > 160 chars, or with non-GSM chars, it will "just work" but if you're optimizing for cost they still show you which encoding is used / how many segments so you can fiddle with that if you need to).

[1] https://www.twilio.com/blog/2017/03/what-the-heck-is-a-segme...