diff --git a/src/cli/README.md b/src/cli/README.md
index b0b20411b..4a9146966 100644
--- a/src/cli/README.md
+++ b/src/cli/README.md
@@ -1348,6 +1348,12 @@ Done
 
 Get the diagnostic information for a Thread Router as parent.
 
+Note: When operating as a Thread Router, this command will return the cached
+      information from when the device was previously attached as a Thread
+      Child. Returning cached information is necessary to support the Thread
+      Test Harness - Test Scenario 8.2.x requests the former parent (i.e. Joiner
+      Router's) MAC address even if the device has already promoted to a router.
+
 ```bash
 > parent
 Ext Addr: be1857c6c21dce55