Write so well that someone doesn’t need to send you a message on Slack to fill the gaps in what you actually wrote about.
Write so well that even someone who barely knows anything about the topic in question can understand everything they need to know while they read your document, one pager or what not.
Write like your writing doesn’t put off someone who already has a fair bit of expertise in the topic, even though you’re trying to make things simple enough for someone new.
Write so clearly that your words continue to make sense even after you die, and there’s no need to wake you up from your grave to truly understand something you wrote.