/tools/sitemap does two things in one call:

• If you give it a sitemap index ( root): we follow no children — we just list them so you can click into each.
• If you give it a sitemap leaf ( root): we count URLs, show the first ten with their lastmod / changefreq / priority if present, and warn if you crossed the 50 000-URL-per-file or 50-MB ceiling that crawlers enforce.

Bare-domain shortcut: enter example.com and we'll automatically try https://example.com/sitemap.xml. Bring your own full URL (https://example.com/sitemap-news.xml) and we use it as-is.

XML parsing via quick-xml — strict, fast, won't accept malformed or non-standard XML. Bad XML returns a precise error message with the byte offset.