From the ticket:

The Connection object is missing some important details about its options parameter. Here are a few of the problems I noticed:

options.port is actually optional and defaults to 27017
options.host is actually optional and defaults to localhost
options.bson is required but undocumented (the constructor will throw if you don't pass it in)
options.tag is undocumented (although I could understand why this one might be omitted based on the comment in the source)
options.maxBsonMessageSize is undocumented
The following SSL-related options are undocumented:
options.ciphers
options.ecdhCurve
I think that covers everything but I may have missed something.

We should update the documentation, but also note that the class is meant to be private and that the API is not guaranteed.