diff --git a/src/fk_graph/cli.py b/src/fk_graph/cli.py
index 40a0262..7808dfb 100644
--- a/src/fk_graph/cli.py
+++ b/src/fk_graph/cli.py
@@ -34,7 +34,11 @@ def _parse_args():
     parser.add_argument("--connection-string")
     parser.add_argument("--table", required=True)
     parser.add_argument("--primary-key", required=True)
-    parser.add_argument("--only-tables", type=_to_list)
+    parser.add_argument(
+        "--only-tables",
+        type=_to_list,
+        help="A list-like JSON string of tables to include.",
+    )
     args = parser.parse_args()
     if (
         (not args.demo and args.connection_string is None)