diff --git a/data/api/client-server/definitions/event_filter.yaml b/data/api/client-server/definitions/event_filter.yaml
index dc3595f18..d03c85daf 100644
--- a/data/api/client-server/definitions/event_filter.yaml
+++ b/data/api/client-server/definitions/event_filter.yaml
@@ -14,7 +14,11 @@
 title: EventFilter
 properties:
   limit:
-    description: The maximum number of events to return. If not specified defaults to 10.
+    description: |
+      The maximum number of events to return, must be an integer greater than 0.
+
+      Servers should apply a default value, and impose a maximum value to avoid
+      resource exhaustion.
     type: integer
   not_senders:
     description: A list of sender IDs to exclude. If this list is absent then no senders