diff --git a/src/dbus/server/introspect.xml b/src/dbus/server/introspect.xml
index 2ae0696179b..449dee38bef 100644
--- a/src/dbus/server/introspect.xml
+++ b/src/dbus/server/introspect.xml
@@ -237,7 +237,8 @@
 
     <!-- ActivateEphemeralKeyMode: Activate ePSKc mode.
       @lifetime: in milliseconds, duration of active ePSKc mode before secure session is established.
-                 0 for OT_BORDER_AGENT_DEFAULT_EPHEMERAL_KEY_TIMEOUT (2 min).
+                 0 for OT_BORDER_AGENT_DEFAULT_EPHEMERAL_KEY_TIMEOUT (2 min). Valid value is [0,
+                 OT_BORDER_AGENT_MAX_EPHEMERAL_KEY_TIMEOUT (10 min)].
       @epskc: returns the ephemeral key digit string of length 9 with first 8 digits randomly generated,
               and the last digit as verhoeff checksum.
     -->