The tool “provides information about Google’s indexed version of a specific page, and also allows you to test whether a URL might be indexable.” The indexed view is not a live test. Results come from the most recently indexed version, so the page may have changed or gone offline since Google last saw it. Use Test live URL to check the current version.
Officially documented · Google Search Console Help
“URL is on Google” means the URL “is eligible to appear in Search results, but is not guaranteed to be there.” For a definitive check, search for the URL on Google. “URL is not on Google” means the URL won’t appear in Search results. The reason is in the Page indexing section.
Officially documented · Google Search Console Help
The Page indexing section answers the usual questions in order:
Field Tells you Discovery Sitemaps and a referring page Google may have found the URL through Crawl allowed? Whether robots.txt blocks the URL Page fetch Whether Google could get the page from your server Indexing allowed? Whether a noindex rule blocks indexing User-declared / Google-selected canonical Your canonical, and the one Google chose
“If your page is blocked by robots.txt (see Crawl allowed?), then Indexing allowed? will always be ‘Yes’ because Google can’t see and respect any noindex directives.” The canonical Google chose appears only in the indexed data. The live test cannot predict whether the tested version will be treated as canonical.
Officially documented · Google Search Console Help
Neither view checks that the page meets quality and security guidelines, manual actions or security issues, content removals, or URLs temporarily blocked in Search Console. A valid live test “only confirms if Google-InspectionTool can access your page for indexing”. Page quality must still be high enough to warrant indexing.
Officially documented · Google Search Console Help
“Submitting a request does not guarantee that the page will appear in the Google Index.” Index requests also have a daily limit. To get many pages indexed, Google suggests submitting a sitemap.
Officially documented · Google Search Console Help
See XML sitemaps for many URLs, and Diagnose a page not indexed by Google for a full troubleshooting order.