It helps check your input domain or page to see if it is being banned from Google Adsense. If it is not, then it is safe to put Adsense code on it to monitize your site. Furthermore, you can use this tool to see if it is safe to purchase a domain or a website, should Adsense AD earning is one of your priorities.
It is 100% accurate on domains and equally or more accurate on pages
You can input a webpage or a domain (with or without the protocol: http or https). Should you input a naked domain; such as: domain.com; the result would mean for the entire domain, subdomains, and all sub pages underneath it
Examples of some acceptable Inputs: