diff --git a/packages/api/src/__tests__/assistant-tools-team-vacation-overlap.test.ts b/packages/api/src/__tests__/assistant-tools-team-vacation-overlap.test.ts
new file mode 100644
index 0000000..1a009d3
--- /dev/null
+++ b/packages/api/src/__tests__/assistant-tools-team-vacation-overlap.test.ts
@@ -0,0 +1,96 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("@capakraken/application", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("@capakraken/application")>();
+  return {
+    ...actual,
+    getDashboardBudgetForecast: vi.fn().mockResolvedValue([]),
+    listAssignmentBookings: vi.fn().mockResolvedValue([]),
+  };
+});
+
+vi.mock("../lib/audit.js", () => ({
+  createAuditEntry: vi.fn().mockResolvedValue(undefined),
+}));
+
+import { executeTool } from "../router/assistant-tools.js";
+import { createToolContext } from "./assistant-tools-holiday-capacity-test-helpers.js";
+
+describe("assistant team vacation overlap tool", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("routes team vacation overlap through the vacation router path", async () => {
+    const db = {
+      resource: {
+        findUnique: vi.fn().mockResolvedValue({
+          id: "res_1",
+          displayName: "Bruce Banner",
+          eid: "BB-1",
+          chapter: "CGI",
+          lcrCents: 0,
+          isActive: true,
+          countryId: null,
+          federalState: null,
+          metroCityId: null,
+          areaRole: null,
+          country: null,
+          metroCity: null,
+        }),
+        findFirst: vi.fn(),
+        findMany: vi.fn(),
+      },
+      vacation: {
+        findMany: vi.fn().mockResolvedValue([
+          {
+            type: "ANNUAL",
+            status: "APPROVED",
+            startDate: new Date("2026-08-10T00:00:00.000Z"),
+            endDate: new Date("2026-08-12T00:00:00.000Z"),
+            resource: { displayName: "Clark Kent" },
+          },
+        ]),
+      },
+    };
+    const ctx = createToolContext(db);
+
+    const result = await executeTool(
+      "get_team_vacation_overlap",
+      JSON.stringify({
+        resourceId: "res_1",
+        startDate: "2026-08-10",
+        endDate: "2026-08-12",
+      }),
+      ctx,
+    );
+
+    expect(db.vacation.findMany).toHaveBeenCalledWith({
+      where: {
+        resource: { chapter: "CGI" },
+        resourceId: { not: "res_1" },
+        status: { in: ["APPROVED", "PENDING"] },
+        startDate: { lte: new Date("2026-08-12T00:00:00.000Z") },
+        endDate: { gte: new Date("2026-08-10T00:00:00.000Z") },
+      },
+      include: {
+        resource: { select: expect.any(Object) },
+      },
+      orderBy: { startDate: "asc" },
+      take: 20,
+    });
+    expect(JSON.parse(result.content)).toEqual(
+      expect.objectContaining({
+        resource: "Bruce Banner",
+        chapter: "CGI",
+        overlapCount: 1,
+        overlappingVacations: [
+          expect.objectContaining({
+            resource: "Clark Kent",
+            status: "APPROVED",
+          }),
+        ],
+      }),
+    );
+  });
+});