XDR? ASN.1? Everything old is new.
ASN.1 is slightly more complex in this regard: BER can be mostly understood without knowledge of it's intended structure but only mostly (actually, MessagePack seems to me like BER done right(-er)), PER requires schema in any case. Bust most significantly ASN.1 is mostly about how to encode the schema itself, which is completely outside of the scope of MessagePack.