diff --git a/package.json b/package.json
index 6c0a2e0..db9462a 100644
--- a/package.json
+++ b/package.json
@@ -13,6 +13,7 @@
     "dev": "tsc -w",
     "format": "prettier --write \"src/**/*.ts\"",
     "lint": "prettier --check \"src/**/*.ts\"",
+    "test": "node --test tests/rest-async-video.test.mjs",
     "prepare": "pnpm run build",
     "pretest": "pnpm run build",
     "inspector": "npx @modelcontextprotocol/inspector build/index.js"
diff --git a/src/services/media-service.ts b/src/services/media-service.ts
index 2ff1947..771b07e 100644
--- a/src/services/media-service.ts
+++ b/src/services/media-service.ts
@@ -133,14 +133,17 @@ export class MediaService extends BaseService {
   public async generateVideo(params: any): Promise<any> {
     this.checkInitialized();
     try {
+      // REST tools expose the option as async_mode, while VideoAPI uses asyncMode.
+      const asyncMode = params.asyncMode ?? params.async_mode;
+
       // Auto-generate output filename if not provided
       if (!params.outputFile) {
         const promptPrefix = params.prompt.substring(0, 20).replace(/[^\w]/g, '_');
         params.outputFile = `video_${promptPrefix}_${Date.now()}`;
       }
 
-      const result = await this.videoApi.generateVideo(params);
-      if (params.async_mode) {
+      const result = await this.videoApi.generateVideo({ ...params, asyncMode });
+      if (asyncMode) {
         return {
           content: [
             {
diff --git a/tests/rest-async-video.test.mjs b/tests/rest-async-video.test.mjs
new file mode 100644
index 0000000..e12adb9
--- /dev/null
+++ b/tests/rest-async-video.test.mjs
@@ -0,0 +1,46 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { MediaService } from '../build/services/media-service.js';
+
+class FakeVideoAPI {
+  constructor() {
+    this.postCalls = [];
+    this.getCalls = [];
+  }
+
+  async post(endpoint, body) {
+    this.postCalls.push({ endpoint, body });
+    return { task_id: 'task-123' };
+  }
+
+  async get(endpoint) {
+    this.getCalls.push(endpoint);
+    throw new Error('video polling should not start for async requests');
+  }
+
+  getResourceMode() {
+    return 'url';
+  }
+}
+
+test('REST async_mode returns the task id without polling', async () => {
+  const api = new FakeVideoAPI();
+  const service = new MediaService(api);
+  await service.initialize({ apiKey: 'test-key', resourceMode: 'url' });
+
+  const result = await service.generateVideo({
+    prompt: 'a test video',
+    async_mode: true,
+  });
+
+  assert.deepEqual(result, {
+    content: [
+      {
+        type: 'text',
+        text: 'Success. Video generation task submitted: Task ID: task-123. Please use `query_video_generation` tool to check the status of the task and get the result.',
+      },
+    ],
+  });
+  assert.equal(api.postCalls.length, 1);
+  assert.equal(api.getCalls.length, 0);
+});