Examining a website value isn't an easy process. It involves measuring everything.. including every factor of the domain, and the website content, promotion scale etc.
So its better if you don't rely on any specific tool to judge the value of a website. They usually take very few factors into consideration.
When valuing a website, check for the domain age, website age(the time its been online), its search engine rankings, the domain name quality, domain name extension, traffic to the website, earnings it has made, depending on the niche and competition. I can't suggest any exact tool, as no website value indicating tool is accurate enough.