It lets you understand the code base at reduced granularity when you want. Or zoom in beyond the written lines to explain _why_ some code is the way it is.
I asked Claude to tell me why something was implemented the way it was, and got an excellent response. One data point, would love to hear more examples.
I agree, Claude has been pretty great at explaining code. It even does well at explaining to me old code that I wrote by hand — including both non-intuitive quirks and flaws.
Claude in its default configuration has untapped potential for explaining and documenting code because it defaults to writing no comments. I added this to my global CLAUDE.md and so far so good:
# Comments
Keep existing comments unless they're wrong
or stale. Err slightly toward adding short
explanatory comments for non-obvious code.