Link extractor / extract links from URL / list all anchor links / page outlink crawler / scrape outbound links / get hrefs from page. Fetches an HTML URL and returns every <a> link with its anchor text, rel attribute, and an is_external flag. Resolves relative URLs against the page's <base> or final URL. Lighter than full scrape / metadata endpoints — exact tool for the agent task 'walk this page, pick which links to follow.' Default 500-link cap. SSRF-guarded (no loopback / RFC1918 targets).