Because it doesn&#x27;t deserialize protocol buffers, but protocol buffer descriptors. Descriptors are serialized protos of this type: <a href="https:&#x2F;&#x2F;github.com&#x2F;google&#x2F;protobuf&#x2F;blob&#x2F;master&#x2F;src&#x2F;google&#x2F;protobuf&#x2F;descriptor.proto" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;google&#x2F;protobuf&#x2F;blob&#x2F;master&#x2F;src&#x2F;google&#x2F;pr...</a> . Each descriptor is a parsed representation of a &quot;.proto&quot; file, including the message names and field names.