The quality tasks start with business rules that need different tests. A required field, an allowed code, and an optional relationship are separate guarantees.
Translate each rule into a failing-row condition or a generic test, then run it. A test that returns valid rows has the wrong meaning even if its SQL is well formed.
You'll also document a capacity model and declare its downstream owner. Keep those descriptions specific to grain and business meaning.
Documentation helps a reader understand a table; tests check data behavior. The final incident asks you to report a warning accurately without treating a completed build as evidence that every row passed.