diff --git a/protocol-spec/json-schema/BaseMessage.schema.json b/protocol-spec/json-schema/BaseMessage.schema.json
index 30ce414..343b1db 100644
--- a/protocol-spec/json-schema/BaseMessage.schema.json
+++ b/protocol-spec/json-schema/BaseMessage.schema.json
@@ -62,6 +62,12 @@
         "type": "object",
         "title": "payload",
         "description": "Message payload (used to store extra information in message, list of permissible fields in the payload depends on \"type\" field)"
+      },
+      "ok": {
+        "$id": "#/properties/ok",
+        "type": "boolean",
+        "title": "ok",
+        "description": "Indicating whether request have an error"
       }
     }
   }
diff --git a/protocol-spec/protocol-errors.md b/protocol-spec/protocol-errors.md
index a9c52c3..159e18f 100644
--- a/protocol-spec/protocol-errors.md
+++ b/protocol-spec/protocol-errors.md
@@ -1,7 +1,7 @@
 # Protocol Errors
 ## Introduction
 Mechanism of error processing included into protocol.  
-Adds into any type ID `:error` postfix.
+Adds into any response message `ok` variable. If `ok` is true - we have no errors, if `ok` is false - we have an error.
 
 ## Message type identifiers
 - `*:error`
@@ -24,9 +24,10 @@ Adds into any type ID `:error` postfix.
 ```json
 {
     "id": "abcd",
-    "type": "incorrectMessageType:error",
+    "type": "incorrectMessageType",
     "from": "cadmium.im",
     "to": "@juliet@cadmium.im",
+    "ok": false,
     "payload": {
         "errCode": 0,
         "errText": "Incorrect type of message (type isn't implemented in the server)",