diff --git a/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/AzureCommunicationServices.json b/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/AzureCommunicationServices.json
index de6017c5b246..528cbebbf7c6 100644
--- a/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/AzureCommunicationServices.json
+++ b/specification/eventgrid/data-plane/Microsoft.Communication/stable/2018-01-01/AzureCommunicationServices.json
@@ -296,7 +296,7 @@
       }
     },
     "AcsChatParticipantAddedToThreadEventData": {
-      "description": "Schema of the Data property of an EventGridEvent for an Microsoft.Communication.ChatParticipantAddedToThread event.",
+      "description": "Schema of the Data property of an EventGridEvent for an Microsoft.Communication.ChatThreadParticipantAdded event.",
       "allOf": [
         {
           "$ref": "#/definitions/AcsChatEventInThreadBaseProperties"
@@ -324,7 +324,7 @@
       }
     },
     "AcsChatParticipantRemovedFromThreadEventData": {
-      "description": "Schema of the Data property of an EventGridEvent for an Microsoft.Communication.ChatParticipantRemovedFromThread event.",
+      "description": "Schema of the Data property of an EventGridEvent for an Microsoft.Communication.ChatThreadParticipantRemoved event.",
       "allOf": [
         {
           "$ref": "#/definitions/AcsChatEventInThreadBaseProperties"
@@ -544,6 +544,10 @@
       "description": "Schema of common properties of all thread-level chat events",
       "type": "object",
       "properties": {
+        "transactionId": {
+          "description": "The transaction id will be used as co-relation vector",
+          "type": "string"
+        },
         "threadId": {
           "description": "The chat thread id",
           "type": "string"