An online system receives tracking requests from client devices interacting with a website to analyze user interactions with the website. The website provides instructions with web pages sent to a client device that cause the client device to send tracking instructions to the online system. The online system sends requests for web pages to the website, receives a plurality of web pages from the website, and determines a count of distinct web pages provided by the website. The online system determines a score for the website indicating a quality of tracking instructions of the website based on various factors, including an aggregate value based on the distinct webpages of the website that include tracking instructions and the count of distinct web pages provided by the website. Based on this score, the online system generates a report describing a quality of the tracking instructions of the website.