diff --git a/protos/services/authentication_service.proto b/protos/services/authentication_service.proto
index 2933b8f..34cc016 100644
--- a/protos/services/authentication_service.proto
+++ b/protos/services/authentication_service.proto
@@ -10,5 +10,11 @@ message SigninRequest {
 }
 
 service AuthenticationService {
+  ///  In the metadata the client will find the Authorization key with the token
+  ///  in the value
   rpc signin(SigninRequest) returns (google.protobuf.Empty);
+
+  /// The client must send in the metadata the Authorization key with the token
+  /// in the value
+  rpc signout(google.protobuf.Empty) returns (google.protobuf.Empty);
 }
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