diff --git a/openapi.yaml b/openapi.yaml
index fa0149c..1fd4984 100644
--- a/openapi.yaml
+++ b/openapi.yaml
@@ -3384,6 +3384,11 @@ paths:
                   format: date-time
                   description: Return only metrics logged at or before this ISO-8601 timestamp.
                   example: "2024-01-01T12:00:00Z"
+                resolution:
+                  type: integer
+                  format: int64
+                  description: Number of (uniformly sampled) train metrics to return.
+                  example: 100
       responses:
         '200':
           description: List of metrics snapshots in chronological order.