diff --git a/docs/api-reference.md b/docs/api-reference.md
index c22c7df..3c1960d 100644
--- a/docs/api-reference.md
+++ b/docs/api-reference.md
@@ -788,6 +788,11 @@ Body:
 
 Response: `200` + `ChatMemberRead`
 
+Rules:
+
+- only `owner` can change member roles.
+- owner cannot demote self from `owner`.
+
 ### DELETE `/api/v1/chats/{chat_id}/members/{user_id}`
 
 Auth required.