diff --git a/packages/agent-runtime/src/tools/handlers/tool/write-file.ts b/packages/agent-runtime/src/tools/handlers/tool/write-file.ts
index 4aa716641d..59a57802ee 100644
--- a/packages/agent-runtime/src/tools/handlers/tool/write-file.ts
+++ b/packages/agent-runtime/src/tools/handlers/tool/write-file.ts
@@ -139,7 +139,7 @@ export const handleWriteFile = (async (
       return {
         tool: 'write_file' as const,
         path,
-        error: `Error: Failed to process the write_file block. ${typeof error === 'string' ? error : error.msg}`,
+        error: `Error: Failed to process the write_file block. ${typeof error === 'string' ? error : error.message}`,
       }
     })
     .then(async (fileProcessingResult) => ({