diff --git a/e2e/sample-apps/modular.js b/e2e/sample-apps/modular.js
index e3170bb3c57..f8b2295768a 100644
--- a/e2e/sample-apps/modular.js
+++ b/e2e/sample-apps/modular.js
@@ -314,13 +314,14 @@ async function callVertexAI(app) {
   console.log('[VERTEXAI] start');
   const vertexAI = getVertexAI(app);
   const model = getGenerativeModel(vertexAI, {
-    mode: 'prefer_in_cloud'
+    mode: 'prefer_on_device'
   });
-  const result = await model.generateContentStream("What is Roko's Basalisk?");
-  for await (const chunk of result.stream) {
-    console.log(chunk.text());
-  }
-  console.log(`[VERTEXAI] counted tokens: ${result.totalTokens}`);
+  const singleResult = await model.generateContent([
+    { text: 'describe the following:' },
+    { text: 'the mojave desert' }
+  ]);
+  console.log(`Generated text: ${singleResult.response.text()}`);
+  console.log(`[VERTEXAI] end`);
 }
 
 /**
@@ -346,18 +347,18 @@ async function main() {
   const app = initializeApp(config);
   setLogLevel('warn');
 
-  callAppCheck(app);
-  await authLogin(app);
-  await callStorage(app);
-  await callFirestore(app);
-  await callDatabase(app);
-  await callMessaging(app);
-  callAnalytics(app);
-  callPerformance(app);
-  await callFunctions(app);
+  // callAppCheck(app);
+  // await authLogin(app);
+  // await callStorage(app);
+  // await callFirestore(app);
+  // await callDatabase(app);
+  // await callMessaging(app);
+  // callAnalytics(app);
+  // callPerformance(app);
+  // await callFunctions(app);
   await callVertexAI(app);
-  callDataConnect(app);
-  await authLogout(app);
+  // callDataConnect(app);
+  // await authLogout(app);
   console.log('DONE');
 }
 
diff --git a/packages/vertexai/src/methods/chrome-adapter.test.ts b/packages/vertexai/src/methods/chrome-adapter.test.ts
index a18812374c0..28a50ceb5eb 100644
--- a/packages/vertexai/src/methods/chrome-adapter.test.ts
+++ b/packages/vertexai/src/methods/chrome-adapter.test.ts
@@ -22,7 +22,8 @@ import { ChromeAdapter } from './chrome-adapter';
 import {
   Availability,
   LanguageModel,
-  LanguageModelCreateOptions
+  LanguageModelCreateOptions,
+  LanguageModelMessageContent
 } from '../types/language-model';
 import { stub } from 'sinon';
 import { GenerateContentRequest } from '../types';
@@ -105,22 +106,6 @@ describe('ChromeAdapter', () => {
         })
       ).to.be.false;
     });
-    it('returns false if request content has multiple parts', async () => {
-      const adapter = new ChromeAdapter(
-        {} as LanguageModel,
-        'prefer_on_device'
-      );
-      expect(
-        await adapter.isAvailable({
-          contents: [
-            {
-              role: 'user',
-              parts: [{ text: 'a' }, { text: 'b' }]
-            }
-          ]
-        })
-      ).to.be.false;
-    });
     it('returns false if request content has non-text part', async () => {
       const adapter = new ChromeAdapter(
         {} as LanguageModel,
@@ -281,7 +266,8 @@ describe('ChromeAdapter', () => {
         create: () => Promise.resolve({})
       } as LanguageModel;
       const languageModel = {
-        prompt: i => Promise.resolve(i)
+        // eslint-disable-next-line @typescript-eslint/no-unused-vars
+        prompt: (p: LanguageModelMessageContent[]) => Promise.resolve('')
       } as LanguageModel;
       const createStub = stub(languageModelProvider, 'create').resolves(
         languageModel
@@ -305,13 +291,8 @@ describe('ChromeAdapter', () => {
       // Asserts Vertex input type is mapped to Chrome type.
       expect(promptStub).to.have.been.calledOnceWith([
         {
-          role: request.contents[0].role,
-          content: [
-            {
-              type: 'text',
-              content: request.contents[0].parts[0].text
-            }
-          ]
+          type: 'text',
+          content: request.contents[0].parts[0].text
         }
       ]);
       // Asserts expected output.
@@ -366,13 +347,8 @@ describe('ChromeAdapter', () => {
       // Asserts Vertex input type is mapped to Chrome type.
       expect(measureInputUsageStub).to.have.been.calledOnceWith([
         {
-          role: 'user',
-          content: [
-            {
-              type: 'text',
-              content: inputText
-            }
-          ]
+          type: 'text',
+          content: inputText
         }
       ]);
       expect(await response.json()).to.deep.equal({
@@ -380,7 +356,7 @@ describe('ChromeAdapter', () => {
       });
     });
   });
-  describe('generateContentStreamOnDevice', () => {
+  describe('generateContentStream', () => {
     it('generates content stream', async () => {
       const languageModelProvider = {
         create: () => Promise.resolve({})
@@ -413,13 +389,8 @@ describe('ChromeAdapter', () => {
       expect(createStub).to.have.been.calledOnceWith(onDeviceParams);
       expect(promptStub).to.have.been.calledOnceWith([
         {
-          role: request.contents[0].role,
-          content: [
-            {
-              type: 'text',
-              content: request.contents[0].parts[0].text
-            }
-          ]
+          type: 'text',
+          content: request.contents[0].parts[0].text
         }
       ]);
       const actual = await toStringArray(response.body!);
diff --git a/packages/vertexai/src/methods/chrome-adapter.ts b/packages/vertexai/src/methods/chrome-adapter.ts
index dcdb38b7fd8..2d18311f4e0 100644
--- a/packages/vertexai/src/methods/chrome-adapter.ts
+++ b/packages/vertexai/src/methods/chrome-adapter.ts
@@ -16,19 +16,15 @@
  */
 
 import {
-  Content,
   CountTokensRequest,
   GenerateContentRequest,
   InferenceMode,
-  Part,
-  Role
+  Part
 } from '../types';
 import {
   Availability,
   LanguageModel,
   LanguageModelCreateOptions,
-  LanguageModelMessage,
-  LanguageModelMessageRole,
   LanguageModelMessageContent
 } from '../types/language-model';
 
@@ -100,8 +96,12 @@ export class ChromeAdapter {
       // TODO: normalize on-device params during construction.
       this.onDeviceParams || {}
     );
-    const messages = ChromeAdapter.toLanguageModelMessages(request.contents);
-    const text = await session.prompt(messages);
+    // TODO: support multiple content objects when Chrome supports
+    // sequence<LanguageModelMessage>
+    const contents = request.contents[0].parts.map(
+      ChromeAdapter.toLanguageModelMessageContent
+    );
+    const text = await session.prompt(contents);
     return ChromeAdapter.toResponse(text);
   }
 
@@ -120,8 +120,12 @@ export class ChromeAdapter {
       // TODO: normalize on-device params during construction.
       this.onDeviceParams || {}
     );
-    const messages = ChromeAdapter.toLanguageModelMessages(request.contents);
-    const stream = await session.promptStreaming(messages);
+    // TODO: support multiple content objects when Chrome supports
+    // sequence<LanguageModelMessage>
+    const contents = request.contents[0].parts.map(
+      ChromeAdapter.toLanguageModelMessageContent
+    );
+    const stream = await session.promptStreaming(contents);
     return ChromeAdapter.toStreamResponse(stream);
   }
 
@@ -131,8 +135,12 @@ export class ChromeAdapter {
       // TODO: normalize on-device params during construction.
       this.onDeviceParams || {}
     );
-    const messages = ChromeAdapter.toLanguageModelMessages(request.contents);
-    const tokenCount = await session.measureInputUsage(messages);
+    // TODO: support multiple content objects when Chrome supports
+    // sequence<LanguageModelMessage>
+    const contents = request.contents[0].parts.map(
+      ChromeAdapter.toLanguageModelMessageContent
+    );
+    const tokenCount = await session.measureInputUsage(contents);
     return {
       json: async () => ({
         totalTokens: tokenCount
@@ -155,10 +163,6 @@ export class ChromeAdapter {
         return false;
       }
 
-      if (content.parts.length > 1) {
-        return false;
-      }
-
       if (!content.parts[0].text) {
         return false;
       }
@@ -188,25 +192,6 @@ export class ChromeAdapter {
       });
   }
 
-  /**
-   * Converts a Vertex role string to a Chrome role string.
-   */
-  private static toOnDeviceRole(role: Role): LanguageModelMessageRole {
-    return role === 'model' ? 'assistant' : 'user';
-  }
-
-  /**
-   * Converts a Vertex Content object to a Chrome LanguageModelMessage object.
-   */
-  private static toLanguageModelMessages(
-    contents: Content[]
-  ): LanguageModelMessage[] {
-    return contents.map(c => ({
-      role: ChromeAdapter.toOnDeviceRole(c.role),
-      content: c.parts.map(ChromeAdapter.toLanguageModelMessageContent)
-    }));
-  }
-
   /**
    * Converts a Vertex Part object to a Chrome LanguageModelMessageContent object.
    */
diff --git a/packages/vertexai/src/types/language-model.ts b/packages/vertexai/src/types/language-model.ts
index b912a1cde21..cd84f22dbdb 100644
--- a/packages/vertexai/src/types/language-model.ts
+++ b/packages/vertexai/src/types/language-model.ts
@@ -56,14 +56,12 @@ interface LanguageModelExpectedInput {
   type: LanguageModelMessageType;
   languages?: string[];
 }
-export type LanguageModelPrompt =
-  | LanguageModelMessage[]
-  | LanguageModelMessageShorthand[]
-  | string;
+// TODO: revert to type from Prompt API explainer once it's supported.
+export type LanguageModelPrompt = LanguageModelMessageContent[];
 type LanguageModelInitialPrompts =
   | LanguageModelMessage[]
   | LanguageModelMessageShorthand[];
-export interface LanguageModelMessage {
+interface LanguageModelMessage {
   role: LanguageModelMessageRole;
   content: LanguageModelMessageContent[];
 }
@@ -75,7 +73,7 @@ export interface LanguageModelMessageContent {
   type: LanguageModelMessageType;
   content: LanguageModelMessageContentValue;
 }
-export type LanguageModelMessageRole = 'system' | 'user' | 'assistant';
+type LanguageModelMessageRole = 'system' | 'user' | 'assistant';
 type LanguageModelMessageType = 'text' | 'image' | 'audio';
 type LanguageModelMessageContentValue =
   | ImageBitmapSource