Reads very well like a donald knuth book, has appropriate humour or engagement as is fun to read, very insightful, should be behind a paywall because it is that good.
It contains polished equations (possibly colorised) or professional looking figures.
It has been seen by other people and regarded as a helpful, informative, elegant solution.
It could be the reason that fans subscribe to patreon etc.
Is sufficiently terse.
gold should be readable by the target audience, possibly everyone. Is production ready.
silver recommendable to a friend, but may need more work to be production ready.
bronze usable by me, but only just.
wood so unreadable that it cannot be used by even me.