diff --git a/src/agents/tools/cron-tool.test.ts b/src/agents/tools/cron-tool.test.ts
index b134d7d7f7c..0d895d95329 100644
--- a/src/agents/tools/cron-tool.test.ts
+++ b/src/agents/tools/cron-tool.test.ts
@@ -105,7 +105,7 @@ describe("cron tool", () => {
       },
     });
 
-    const call = callGatewayMock.mock.calls[0]?.[0] as {
+    const call = callGatewayMock.mock.calls.at(0)?.[0] as {
       params?: { delivery?: TestDelivery };
     };
     return call?.params?.delivery;
@@ -534,7 +534,7 @@ describe("cron tool", () => {
       },
     });
 
-    const call = callGatewayMock.mock.calls[0]?.[0] as {
+    const call = callGatewayMock.mock.calls.at(0)?.[0] as {
       params?: { agentId?: unknown };
     };
     expect(call?.params?.agentId).toBeNull();
@@ -721,7 +721,7 @@ describe("cron tool", () => {
       },
     });
 
-    const call = callGatewayMock.mock.calls[0]?.[0] as {
+    const call = callGatewayMock.mock.calls.at(0)?.[0] as {
       method?: string;
       params?: { agentId?: string | null };
     };
@@ -1066,7 +1066,7 @@ describe("cron tool", () => {
       name: "flat-name-should-be-ignored",
     });
 
-    const call = callGatewayMock.mock.calls[0]?.[0] as {
+    const call = callGatewayMock.mock.calls.at(0)?.[0] as {
       params?: { name?: string; payload?: { text?: string } };
     };
     expect(call?.params?.name).toBe("nested-job");
diff --git a/src/agents/tools/sessions-spawn-tool.test.ts b/src/agents/tools/sessions-spawn-tool.test.ts
index 0d539daa323..2bba41107b8 100644
--- a/src/agents/tools/sessions-spawn-tool.test.ts
+++ b/src/agents/tools/sessions-spawn-tool.test.ts
@@ -668,10 +668,8 @@ describe("sessions_spawn tool", () => {
     expect(spawnArgs.task).toBe("resume prior work");
     const spawnContext = mockCallArg(hoisted.spawnSubagentDirectMock, 0, 1, "spawnSubagentDirect");
     expect(spawnContext.agentSessionKey).toBe("agent:main:main");
-    expect(hoisted.spawnSubagentDirectMock.mock.calls[0]?.[0]).not.toHaveProperty(
-      "resumeSessionId",
-    );
-    expect(hoisted.spawnSubagentDirectMock.mock.calls[0]?.[0]).not.toHaveProperty("streamTo");
+    expect(spawnArgs).not.toHaveProperty("resumeSessionId");
+    expect(spawnArgs).not.toHaveProperty("streamTo");
     expect(hoisted.spawnAcpDirectMock).not.toHaveBeenCalled();
   });
 
@@ -717,10 +715,8 @@ describe("sessions_spawn tool", () => {
     expect(hoisted.spawnAcpDirectMock).not.toHaveBeenCalled();
     const spawnArgs = mockCallArg(hoisted.spawnSubagentDirectMock, 0, 0, "spawnSubagentDirect");
     expect(spawnArgs.task).toBe("analyze file");
-    expect(hoisted.spawnSubagentDirectMock.mock.calls[0]?.[0]).not.toHaveProperty(
-      "resumeSessionId",
-    );
-    expect(hoisted.spawnSubagentDirectMock.mock.calls[0]?.[0]).not.toHaveProperty("streamTo");
+    expect(spawnArgs).not.toHaveProperty("resumeSessionId");
+    expect(spawnArgs).not.toHaveProperty("streamTo");
   });
 
   it('treats model="default" as no explicit model override', async () => {
diff --git a/src/agents/tools/video-generate-tool.test.ts b/src/agents/tools/video-generate-tool.test.ts
index 19f6cc49b2e..28f3b2c7076 100644
--- a/src/agents/tools/video-generate-tool.test.ts
+++ b/src/agents/tools/video-generate-tool.test.ts
@@ -156,7 +156,7 @@ function resultDetails(result: { details?: unknown }): Record<string, unknown> {
 }
 
 function firstMockCallArg(mock: { mock: { calls: unknown[][] } }): unknown {
-  const firstCall = mock.mock.calls[0];
+  const firstCall = mock.mock.calls.at(0);
   if (!firstCall) {
     throw new Error("Expected first mock call");
   }
@@ -399,7 +399,7 @@ describe("createVideoGenerateTool", () => {
     });
 
     expect((firstMockCallArg(generateSpy) as { timeoutMs?: number }).timeoutMs).toBe(180_000);
-    expect((generateSpy.mock.calls[1]?.[0] as { timeoutMs?: number }).timeoutMs).toBe(12_345);
+    expect((generateSpy.mock.calls.at(1)?.[0] as { timeoutMs?: number }).timeoutMs).toBe(12_345);
     expect(resultDetails(defaultResult).timeoutMs).toBe(180_000);
     expect(resultDetails(overrideResult).timeoutMs).toBe(12_345);
   });
@@ -1059,7 +1059,7 @@ describe("createVideoGenerateTool", () => {
     });
 
     expect(generateSpy).toHaveBeenCalledTimes(1);
-    const call = generateSpy.mock.calls[0]?.[0] as {
+    const call = generateSpy.mock.calls.at(0)?.[0] as {
       inputImages?: Array<{ role?: string }>;
     };
     expect(call.inputImages).toHaveLength(2);
@@ -1096,7 +1096,7 @@ describe("createVideoGenerateTool", () => {
       image: "/tmp/reference.png",
     });
 
-    const loadCall = vi.mocked(webMedia.loadWebMedia).mock.calls[0];
+    const loadCall = vi.mocked(webMedia.loadWebMedia).mock.calls.at(0);
     expect(loadCall?.[0]).toBe("/tmp/reference.png");
     const loadOptions = loadCall?.[1] as { ssrfPolicy?: unknown } | undefined;
     expect(loadOptions?.ssrfPolicy).toEqual({ allowRfc2544BenchmarkRange: true });