Background
On-page meta tags still matter. The title and meta description are what Google shows in the search snippet (when it doesn't rewrite them). The H1 reinforces topical relevance. The canonical tag tells search engines which URL is the authoritative version of the page when duplicates exist. Get any of these wrong (too long, too short, missing, or pointing somewhere unexpected) and you leave clicks on the table.
This tool reads the page metadata from our web index, so it shows what Google's crawler most recently saw, not necessarily what your CMS thinks it's serving. That distinction matters: client-side rendering bugs and stale CDN caches often mean the indexed tags differ from the live HTML.