diff --git a/lib/features/settings/preferences_mcp_section.dart b/lib/features/settings/preferences_mcp_section.dart
index 48a09c71..c4300c39 100644
--- a/lib/features/settings/preferences_mcp_section.dart
+++ b/lib/features/settings/preferences_mcp_section.dart
@@ -349,6 +349,11 @@ class _ActivityRow extends material.StatelessWidget {
             style: material.TextStyle(
                 color: entry.error != null ? wb.destructive : wb.mutedForeground),
           ).xSmall(),
+          // The guard rule that refused the call, when one did.
+          if (entry.refusalRule != null)
+            Text('refused by ${entry.refusalRule}')
+                .xSmall()
+                .muted(),
         ],
       ),
     );
diff --git a/test/features/settings/preferences_mcp_section_test.dart b/test/features/settings/preferences_mcp_section_test.dart
index 1c64c521..e07200e2 100644
--- a/test/features/settings/preferences_mcp_section_test.dart
+++ b/test/features/settings/preferences_mcp_section_test.dart
@@ -184,6 +184,7 @@ void main() {
         sqlText: 'DELETE FROM orders',
         durationMs: 1,
         error: 'Data-modifying statements are not allowed over MCP.',
+        refusalRule: 'data_modifying',
       ),
     ];
     await pump(tester);
@@ -192,6 +193,7 @@ void main() {
     expect(find.text('1 row(s) · 12 ms'), findsOneWidget);
     expect(find.text('Data-modifying statements are not allowed over MCP.'),
         findsOneWidget);
+    expect(find.text('refused by data_modifying'), findsOneWidget);
 
     await tester.tap(find.byKey(const material.ValueKey('mcp_clear_log')));
     await tester.pump();