diff --git a/apps/ai-game-creator-shell/src-tauri/src/agent_native_tools.rs b/apps/ai-game-creator-shell/src-tauri/src/agent_native_tools.rs
index 1b582897f..9ead2654a 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/agent_native_tools.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/agent_native_tools.rs
@@ -1475,7 +1475,7 @@ fn runtime_tool_description(tool: &str) -> &'static str {
         "blackboard.write" => "向项目级共享黑板追加稳定结论。",
         "agent.message" => "向一个目标 Agent 写入定向上下文消息。",
         "agent.delegate" => {
-            "用持久验收合同把边界清晰的后台任务委派给另一个 Agent；返工时 repairOfDelegationId 指向原 delivery，且 runId 必须为 null。"
+            "用持久验收合同把边界清晰的后台任务委派给另一个 Agent；返工时 repairOfDelegationId 指向原 delivery，runId 必须为 null，acceptanceCriteria 与 expectedArtifacts 一起传 null 由 Runtime 从原 delivery 继承。"
         }
         "agent.spawn_isolated" => "创建最多三个写范围互不重叠的隔离子 Agent。",
         "agent.goal_contract" => {
@@ -1722,8 +1722,8 @@ fn runtime_tool_input_schema(tool: &str) -> Value {
             "properties": {
                 "agentId": { "type": "string", "minLength": 1 },
                 "task": { "type": "string", "minLength": 1, "maxLength": 2400 },
-                "acceptanceCriteria": { "type": "array", "minItems": 1, "maxItems": 8, "items": { "type": "string", "minLength": 1, "maxLength": 240 } },
-                "expectedArtifacts": { "type": "array", "maxItems": 16, "items": { "type": "string", "minLength": 1, "maxLength": 240 } },
+                "acceptanceCriteria": { "type": ["array", "null"], "minItems": 1, "maxItems": 8, "items": { "type": "string", "minLength": 1, "maxLength": 240 }, "description": "初次委派必填。带 repairOfDelegationId 的返工或澄清续跑传 null：Runtime 会从原 delivery 继承权威合同，手抄一遍不增加任何信息，抄错会被直接拒收。" },
+                "expectedArtifacts": { "type": ["array", "null"], "maxItems": 16, "items": { "type": "string", "minLength": 1, "maxLength": 240 }, "description": "与 acceptanceCriteria 同进同出：初次委派必填，返工与澄清续跑一起传 null 由 Runtime 继承。" },
                 "repairOfDelegationId": { "type": ["string", "null"] },
                 "runId": { "type": ["string", "null"] },
                 "continuationOfDelegationId": { "type": ["string", "null"] },
@@ -2214,6 +2214,22 @@ mod tests {
 
         assert!(description.contains("repairOfDelegationId 指向原 delivery"));
         assert!(description.contains("runId 必须为 null"));
+        // 广告给模型的 schema 一度把这两个数组写死成非空数组，模型于是根本无法
+        // 传 null，只能手抄——实测每条 continuation 固定先失败 2 次才抄对。
+        assert!(
+            description.contains("acceptanceCriteria 与 expectedArtifacts 一起传 null"),
+            "{description}"
+        );
+        let schema = runtime_tool_input_schema("agent.delegate");
+        for field in ["acceptanceCriteria", "expectedArtifacts"] {
+            let types = schema["properties"][field]["type"]
+                .as_array()
+                .unwrap_or_else(|| panic!("{field} 必须允许 null"));
+            assert!(
+                types.iter().any(|value| value == "null"),
+                "{field} 的广告 schema 必须允许 null，否则 Runtime 侧的继承分支永远走不到"
+            );
+        }
     }
 
     /// plan 根 Supervisor 只广告 7 个原生工具 + 2 个协议控制。全量注册表里其余