diff --git a/gerrit_util.py b/gerrit_util.py
index a7619c3..323e269 100644
--- a/gerrit_util.py
+++ b/gerrit_util.py
@@ -223,7 +223,11 @@
@classmethod
def is_applicable(cls, *, conn: Optional[HttpConn] = None) -> bool:
"""Must return True if this Authenticator is available in the current
- environment."""
+ environment.
+
+ If conn is not None, return True if this Authenticator is
+ applicable to the given conn in the current environment.
+ """
raise NotImplementedError()
def ensure_authenticated(self, gerrit_host: str, git_host: str) -> Tuple[bool, str]: