diff --git a/packages/stage-ui/src/tools/mcp.ts b/packages/stage-ui/src/tools/mcp.ts
index 3bbe54e37..1d174d56d 100644
--- a/packages/stage-ui/src/tools/mcp.ts
+++ b/packages/stage-ui/src/tools/mcp.ts
@@ -13,7 +13,7 @@ const tools = [
       }
       catch (error) {
         console.warn('[mcp_list_tools] failed to list tools:', error)
-        return []
+        return ''
       }
     },
     parameters: z.object({}).strict(),