diff --git a/metrics/auth.go b/metrics/auth.go
index db1ec09..ae7906c 100644
--- a/metrics/auth.go
+++ b/metrics/auth.go
@@ -1,3 +1,4 @@
+// Package metrics has (prometheus) metrics shared between components of mox, e.g. for authentication.
 package metrics
 
 import (