diff --git a/credentials/credentials.go b/credentials/credentials.go
index 5f103640..ad75f954 100644
--- a/credentials/credentials.go
+++ b/credentials/credentials.go
@@ -112,6 +112,8 @@ type TransportAuthenticator interface {
 	Credentials
 }
 
+// TLSInfo contains the auth information for a TLS authenticated connection.
+// It implements the AuthInfo interface.
 type TLSInfo struct {
 	state tls.ConnectionState
 }