diff --git a/protos/src/main/protobuf/blockstream.proto b/protos/src/main/protobuf/blockstream.proto
index ac0fd2c78..87ff477f7 100644
--- a/protos/src/main/protobuf/blockstream.proto
+++ b/protos/src/main/protobuf/blockstream.proto
@@ -32,7 +32,19 @@ option java_outer_classname = "BlockStreamServiceGrpcProto";
   * with the id of each block received.
  */
 service BlockStreamGrpc {
+
+    /**
+     * StreamSink is a bidirectional streaming method that allows a producer to stream blocks
+     * to the Block Node server.  The server will respond with a BlockResponse message for each
+     * block received.
+     */
     rpc StreamSink(stream Block) returns (stream BlockResponse) {}
+
+    /**
+     * StreamSource is a bidirectional streaming method that allows a consumer to request a
+     * stream of blocks from the server.  The consumer is expected to respond with a BlockResponse
+     * message with the id of each block received.
+     */
     rpc StreamSource(stream BlockResponse) returns (stream Block) {}
 }