diff --git a/apps/ai-game-creator-shell/src-tauri/src/agent/direct_tools_mcp.rs b/apps/ai-game-creator-shell/src-tauri/src/agent/direct_tools_mcp.rs
index a7fa9eb0c..bb52090bb 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/agent/direct_tools_mcp.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/agent/direct_tools_mcp.rs
@@ -1745,7 +1745,11 @@ where
                             });
                             None
                         }
-                        Err(_) => Some(mcp_error(Value::Null, -32700, "Parse error")),
+                        Err(error) => Some(mcp_error(
+                            Value::Null,
+                            -32700,
+                            &format!("Parse error: {error}"),
+                        )),
                     },
                     Some(Err(error)) => {
                         terminal_error = Some(error);
@@ -2336,7 +2340,12 @@ mod tests {
             .map(|line| serde_json::from_str::<Value>(line).unwrap())
             .collect::<Vec<_>>();
         assert_eq!(replies.len(), 2);
-        assert!(replies.iter().any(|reply| reply["error"]["code"] == -32700));
+        assert!(replies.iter().any(|reply| {
+            reply["error"]["code"] == -32700
+                && reply["error"]["message"]
+                    .as_str()
+                    .is_some_and(|message| message.contains("Parse error"))
+        }));
         assert!(replies
             .iter()
             .any(|reply| reply["id"] == "failed-call" && reply["error"]["code"] == -32603));
diff --git a/docs/project-memory/shared-memory/pitfalls.md b/docs/project-memory/shared-memory/pitfalls.md
index 49d0ea922..fd828c187 100644
--- a/docs/project-memory/shared-memory/pitfalls.md
+++ b/docs/project-memory/shared-memory/pitfalls.md
@@ -18,6 +18,8 @@
 
 资源画布预览失败态也必须优先显示 `previewError`；只有宿主确实没有正文时才显示“未提供具体错误正文”，不能把已有的读取、解码或权限原因改成单独的“预览失败”。
 
+MCP stdio 收到非法 JSON 时，JSON-RPC `-32700` 响应也要保留解析器正文（不回显原始请求），不能只返回一个无上下文的 `Parse error`。
+
 ## 2026-10-03 AGC 随包 plugins 的 feature 档位必须与消费方一致，且门禁会因 build.rs 未重跑而假通过
 
 - **现象**：Windows 本机 `npm run check:generated-bindings`（`npm run lint` 链内，`scripts/check-repository-ci.sh` 的 Repository checks 也走它）在 `build.rs:167:29` panic：`插件随包资源校验失败：随包插件存在未声明文件：.../src-tauri/resources/plugins/agc-godot-editor/native/gdextension/bin/win-x64/agc_godot_editor.dll（目标 x86_64-pc-windows-msvc 与当前 feature 组合不允许；请先执行随包资源准备步骤）`；树上换成 `agc-unity-editor/dotnet/publish/win-x64/Agc.Unity.Attach.exe` 时报同一类错。反向还有更隐蔽的形态：门禁 2 秒就 exit 0 说「通过」，但 tree 上其实带着编辑器产物。