diff --git a/tools/testing/selftests/net/mptcp/diag.sh b/tools/testing/selftests/net/mptcp/diag.sh
index 776d43a6922d..0b8ff6e7fa52 100755
--- a/tools/testing/selftests/net/mptcp/diag.sh
+++ b/tools/testing/selftests/net/mptcp/diag.sh
@@ -75,6 +75,13 @@ __chk_msk_nr()
 	local condition=$1
 	shift 1
 
+	# ss: dumps socket statistics
+	# -i/--info: show internal TCP information
+	# -n/--numeric: prefer machine output to human output
+	# -m/--memory: show socket memory usage
+	# -H/--no-header: don't print header
+	# -M/--mptcp: display mptcp sockets
+	# -N/--net: use specified network namespace name
 	__chk_nr "ss -inmHMN $ns | $condition" "$@"
 }