diff --git a/src/agents/pi-embedded-helpers.iscloudcodeassistformaterror.test.ts b/src/agents/pi-embedded-helpers.iscloudcodeassistformaterror.test.ts
index 2433642e4..b746f3fec 100644
--- a/src/agents/pi-embedded-helpers.iscloudcodeassistformaterror.test.ts
+++ b/src/agents/pi-embedded-helpers.iscloudcodeassistformaterror.test.ts
@@ -16,6 +16,7 @@ describe("isCloudCodeAssistFormatError", () => {
       "messages.1.content.1.tool_use.id",
       "tool_use.id should match pattern",
       "invalid request format",
+      "Field required",
     ];
     for (const sample of samples) {
       expect(isCloudCodeAssistFormatError(sample)).toBe(true);
diff --git a/src/agents/pi-embedded-helpers/errors.ts b/src/agents/pi-embedded-helpers/errors.ts
index 9bc92f259..954a3d894 100644
--- a/src/agents/pi-embedded-helpers/errors.ts
+++ b/src/agents/pi-embedded-helpers/errors.ts
@@ -395,6 +395,7 @@ const ERROR_PATTERNS = {
     "tool_use_id",
     "messages.1.content.1.tool_use.id",
     "invalid request format",
+    "field required",
   ],
 } as const;