diff --git a/docs/design/autoware-interfaces/ad-api/list/api/routing/set_route.md b/docs/design/autoware-interfaces/ad-api/list/api/routing/set_route.md
index d80b8ac5138..a7338b1c45c 100644
--- a/docs/design/autoware-interfaces/ad-api/list/api/routing/set_route.md
+++ b/docs/design/autoware-interfaces/ad-api/list/api/routing/set_route.md
@@ -19,4 +19,5 @@ type:
 {% extends 'design/autoware-interfaces/templates/autoware-interface.jinja2' %}
 {% block description %}
 Set the route with the waypoint segments in lanelet format. If start pose is not specified, the current pose will be used.
+This API only accepts the route when the route state is UNSET. In any other state, clear the route first.
 {% endblock %}
diff --git a/docs/design/autoware-interfaces/ad-api/list/api/routing/set_route_points.md b/docs/design/autoware-interfaces/ad-api/list/api/routing/set_route_points.md
index 0b80cf71ecd..b95f8fae903 100644
--- a/docs/design/autoware-interfaces/ad-api/list/api/routing/set_route_points.md
+++ b/docs/design/autoware-interfaces/ad-api/list/api/routing/set_route_points.md
@@ -19,4 +19,5 @@ type:
 {% extends 'design/autoware-interfaces/templates/autoware-interface.jinja2' %}
 {% block description %}
 Set the route with the waypoint poses. If start pose is not specified, the current pose will be used.
+This API only accepts the route when the route state is UNSET. In any other state, clear the route first.
 {% endblock %}