What does IndexNow tell a search engine?

It sends a notice about a specific changed page. The engine can decide when to fetch it and what to index. An accepted notice shows the address was received. It does not tell you whether the new content appears in search.

Which pages belong in a notice?

Use changed public addresses on the site you control. The protocol uses a key file on the site to demonstrate control. A publishing integration can send notices, but it should leave private previews, unchanged pages and unrelated domains out. Participating engines can share submitted addresses within the protocol.

What should your team keep when changing integrations?

Keep a clean list of the pages and change types your publishing workflow sends, along with response status and time. The protocol defines batches up to 10,000 addresses per request. Its documentation also describes responses for key or submission problems. Preserve these rules so you can replace an integration without guessing which pages it notified.

Which of three pages should trigger a notice?

Sketch a fictional release with a changed public help page, an unchanged home page and a private preview. Decide what your site would include before enabling a real integration.

Include the one public change
Write down the public help page. Leave out the unchanged home page and preview.
Separate two records
Mark whether a notice was accepted, then leave indexing as unknown until you see an engine report.