tagKeyBoundaries

Enter the existing custom tag keys for custom applications in your system. Resource tags help CloudWatch investigations narrow the search space when it is unable to discover definite relationships between resources. For example, to discover that an Amazon ECS service depends on an Amazon RDS database, CloudWatch investigations can discover this relationship using data sources such as X-Ray and CloudWatch Application Signals. However, if you haven't deployed these features, CloudWatch investigations will attempt to identify possible relationships. Tag boundaries can be used to narrow the resources that will be discovered by CloudWatch investigations in these cases.

You don't need to enter tags created by myApplications or CloudFormation, because CloudWatch investigations can automatically detect those tags.