Sections are self-contained. When a section says "it also supports this" the reader of the page knows what "it" is.
The check reads sections one at a time, without the rest of the page, and asks whether each names its subject and states its answer. Retrieval returns passages, not pages — a passage that depends on the paragraph above it loses its meaning when quoted alone.
When a section says "it also supports this" the reader of the page knows what "it" is. The engine that retrieved only that section does not. Self-contained sections get used; dependent ones are skipped or misread.
Copy one section into an empty document and read it. If you cannot tell what it is about or what it claims, neither can a retriever.
What the agent does: the agent rewrites a section to stand alone — subject named, claim stated — for your approval.
Part of the 23 checks · group: Page content — text without JavaScript, response time, internal links, answer-first structure, self-contained sections, headings/dates/authorship.
As long as one idea needs. Retrievers chunk long pages; a section of two to six paragraphs with a clear heading survives chunking best.
The page check reads your public pages from outside and runs all 22 — free, no signup, no AI engine involved.