diff --git a/tools/schemas/autoplay/turn-stats-line.json b/tools/schemas/autoplay/turn-stats-line.json
index 7189b6f1..50840dee 100644
--- a/tools/schemas/autoplay/turn-stats-line.json
+++ b/tools/schemas/autoplay/turn-stats-line.json
@@ -149,6 +149,25 @@
           "type": "integer",
           "minimum": 0,
           "description": "Total wonders owned by this player at this snapshot. 0 valid."
+        },
+        "mcts_action": {
+          "type": ["string", "null"],
+          "description": "MCTS-chosen strategic action this turn (e.g. 'Idle', 'FoundCity', 'SpawnUnit'). Added by GdMcTreeController instrumentation. Optional."
+        },
+        "mcts_root_found": {
+          "type": "integer",
+          "minimum": 0,
+          "description": "MCTS root visit count for FoundCity action. Optional MCTS instrumentation."
+        },
+        "mcts_root_idle": {
+          "type": "integer",
+          "minimum": 0,
+          "description": "MCTS root visit count for Idle action. Optional MCTS instrumentation."
+        },
+        "mcts_root_spawn": {
+          "type": "integer",
+          "minimum": 0,
+          "description": "MCTS root visit count for SpawnUnit action. Optional MCTS instrumentation."
         }
       }
     }