diff --git a/tests/test_mcp_tool_rulebooks.py b/tests/test_mcp_tool_rulebooks.py
index 932fc84..8110cc3 100644
--- a/tests/test_mcp_tool_rulebooks.py
+++ b/tests/test_mcp_tool_rulebooks.py
@@ -206,8 +206,10 @@ def test_register_attaches_every_tool():
     # always-on exclusion tools with the tier they served.
     # 22 since milestone 414 retired subscriptions and suppressions: the two
     # subscribe tools and the four suppress/unsuppress tools. 23 with move_rule
-    # (milestone 414 step 3), the way a rule changes home.
-    assert len(mcp.names) == 23
+    # (milestone 414 step 3), the way a rule changes home. 24 with
+    # rule_outcome (milestone 419 step 1), the way a rule says what it
+    # actually changed.
+    assert len(mcp.names) == 24
     # spot-check a few names
     assert "list_rulebooks" in mcp.names
     assert "create_rule" in mcp.names