As an agency dealing with tens of thousands of URLs, it’s inevitable that some of them are going to break without our knowledge.
Not only does sending traffic to a broken link waste ad spend, it also leads to a poor experience for the user. Redirecting links can also strip out tracking code, preventing us from accurately seeing the impact of our activity. In order to mitigate this, we’ve set up a Google Apps Script to automatically scan all active ads in our MCC account and send a notification to Slack (or via email) whenever it detects a problem.
Source: Creating a Slackbot to Scan Google Ads URLs for Errors