I pruned my Claude.md and it made a difference. There were entries there that evolved from earlier models and Opus 5 could be reacting to it in a different manner.

They added a config option to Claude Code to make the output concise, and promised more comprehensive improvements.

I did not see an explanation though.

They say you aren't interacting with an LLM or a model, but the character that the LLM is playing - the "always be positive and helpful software engineer"

Producing more tokens means charging more money to solve a given task.

The brevity how it outputs words seems like they try to save on tokens delivered.