Where is the mandatory human readable prose description of the purpose of the tool in any of those specs. It isn't. Also the simplicity of JSON interface descriptions is key.

You can’t connect to a gRPC endpoint and ask to download the client protobuf, but yes.

It's not enabled by default, but you can --- gRPC Reflection:

* https://github.com/grpc/grpc-java/blob/master/documentation/...

* https://grpc.io/docs/guides/reflection/

You can then use generic tools like grpc_cli or grpcurl to list available services and methods, and call them.