diff --git a/src/agents/tools/cron-tool.test.ts b/src/agents/tools/cron-tool.test.ts
index 4b725ac15650..2e309a6820c3 100644
--- a/src/agents/tools/cron-tool.test.ts
+++ b/src/agents/tools/cron-tool.test.ts
@@ -477,22 +477,18 @@ describe("cron tool", () => {
     expect(jobDelivery?.properties?.channel?.type).toBe("string");
     expect(jobDelivery?.properties?.failureDestination?.anyOf).toBeUndefined();
     expect(jobDelivery?.properties?.failureDestination?.type).toBe("object");
-    expect(patch?.properties?.agentId?.anyOf?.map((entry) => entry.type)).toEqual([
-      "string",
-      "null",
-    ]);
-    expect(patch?.properties?.sessionKey?.anyOf?.map((entry) => entry.type)).toEqual([
-      "string",
-      "null",
-    ]);
-    expect(payload?.properties?.toolsAllow?.anyOf?.map((entry) => entry.type)).toEqual([
-      "array",
-      "null",
-    ]);
-    expect(delivery?.properties?.channel?.anyOf?.map((entry) => entry.type)).toEqual([
-      "string",
-      "null",
-    ]);
+    expect(patch?.properties?.agentId?.anyOf).toBeUndefined();
+    expect(patch?.properties?.agentId?.type).toBe("string");
+    expect(patch?.properties?.agentId?.description).toContain("null to clear");
+    expect(patch?.properties?.sessionKey?.anyOf).toBeUndefined();
+    expect(patch?.properties?.sessionKey?.type).toBe("string");
+    expect(patch?.properties?.sessionKey?.description).toContain("null to clear");
+    expect(payload?.properties?.toolsAllow?.anyOf).toBeUndefined();
+    expect(payload?.properties?.toolsAllow?.type).toBe("array");
+    expect(payload?.properties?.toolsAllow?.description).toContain("null to clear");
+    expect(delivery?.properties?.channel?.anyOf).toBeUndefined();
+    expect(delivery?.properties?.channel?.type).toBe("string");
+    expect(delivery?.properties?.channel?.description).toContain("null to clear");
     expect(delivery?.properties?.failureDestination?.anyOf?.map((entry) => entry.type)).toEqual([
       "object",
       "null",
diff --git a/src/agents/tools/cron-tool.ts b/src/agents/tools/cron-tool.ts
index 9416fb57ecdf..71e06e030d09 100644
--- a/src/agents/tools/cron-tool.ts
+++ b/src/agents/tools/cron-tool.ts
@@ -79,7 +79,7 @@ function nullableStringArraySchema(description: string) {
 
 function deliveryStringSchema(params: { description: string; nullableClears: boolean }) {
   return params.nullableClears
-    ? nullableStringSchema(params.description)
+    ? nullableStringSchema(`${params.description}, or null to clear`)
     : Type.Optional(Type.String({ description: params.description }));
 }