diff --git a/changelog.d/16631.doc b/changelog.d/16631.doc
new file mode 100644
index 000000000000..1128a080eaf7
--- /dev/null
+++ b/changelog.d/16631.doc
@@ -0,0 +1 @@
+Update parameter information for the `/timestamp_to_event` admin API.
diff --git a/docs/admin_api/rooms.md b/docs/admin_api/rooms.md
index 90b06045a820..ad011e5c36e6 100644
--- a/docs/admin_api/rooms.md
+++ b/docs/admin_api/rooms.md
@@ -536,7 +536,8 @@ The following query parameters are available:
 
 **Response**
 
-* `event_id` - converted from timestamp
+* `event_id` - The event ID closest to the given timestamp.
+* `origin_server_ts` - The timestamp of the event in milliseconds since the Unix epoch.
 
 # Block Room API
 The Block Room admin API allows server admins to block and unblock rooms,