Good software is correct. If your software is not correct, it’s bad software.

Bugs make your software incorrect. So buggy software is incorrect software.

Good software is efficient. I mean this in as many ways as you can think of - performance, usability, etc. If your software is not efficient, it’s bad software.

Good software is easy to change. Change is a fundamental property of software - requirements change, goals change, users change, technologies change. If it’s hard to change your software, it’s bad software.

Even if agents are the ones writing the software, it's much cheaper if they don't have to rewrite all of it every time you ask for a change.