The "Getting Full Collection Information" section of the collection enumeration spec mentions that the output of the listCollections helper method must remain the same regardless of whether it is performed via a listCollections command or via a query over the legacy system.namespaces collection in pre 3.0 servers. However, since the 3.0 release, new fields were added to the listCollections command response (e.g. info) that would be omitted according to a strict reading of the collection enumeration spec. This spec should be updated to relax this requirement and allow for future additive changes to the listCollections command response.

The relevant quote:

The returned result for each variant MUST be equivalent, and each collection that is returned MUST use the field names name and options.

On a more general note: the collection enumeration spec is currently listed as a "Draft", despite having been written in 2015. We should update this spec and put it through the formal approval process.