Mongo Atlas API - Get Databases and Collections in a Cluster
The MongoDB Atlas API is for programmatic access to Atlas' management, monitoring, and backup  features. API connections are to the Atlas service, not to the underlying MongoDB clusters.

To query data in your clusters (for example, listing database and collections) you need to connect to each cluster using an authenticated MongoDB driver or client.


  I want to avoid having to connect to each cluster and collecting this information with a query - this is for a service discovery tool I am building for inventorying purposes.


This is the currently the only supported approach.