promptfoo/site/docs/providers/vertex.md

sidebar_label	title	description
Google Vertex	Google Vertex AI Provider	Use Google Vertex AI models including Gemini, Claude, Llama, and specialized models for text, code, and embeddings in your evals

Google Vertex

The vertex provider enables integration with Google's Vertex AI platform, which provides access to foundation models including Gemini, PaLM (Bison), Llama, Claude, and specialized models for text, code, and embeddings.

Available Models

Latest Gemini Models

• vertex:gemini-2.5-pro - Latest stable Gemini 2.5 Pro model with enhanced reasoning, coding, and multimodal understanding (2M context)
• vertex:gemini-2.5-flash - Latest stable Flash model with enhanced reasoning and thinking capabilities
• vertex:gemini-2.5-flash-lite - Most cost-efficient and fastest 2.5 model yet, optimized for high-volume, latency-sensitive tasks
• vertex:gemini-2.0-pro - Strongest model quality, especially for code & world knowledge with 2M context window
• vertex:gemini-2.0-flash-thinking-exp - Enhanced reasoning capabilities with thinking process in responses
• vertex:gemini-2.0-flash-001 - Workhorse model for all daily tasks with strong overall performance and real-time streaming
• vertex:gemini-2.0-flash-lite-preview-02-05 - Cost-effective offering for high throughput
• vertex:gemini-1.5-flash - Fast and efficient for high-volume, quality, cost-effective applications
• vertex:gemini-1.5-pro - Strong performance for text/chat with long-context understanding
• vertex:gemini-1.5-pro-latest - Latest Gemini 1.5 Pro model with same capabilities as gemini-1.5-pro
• vertex:gemini-1.5-flash-8b - Small model optimized for high-volume, lower complexity tasks

Claude Models

Anthropic's Claude models are available with the following versions:

• vertex:claude-opus-4-1@20250805 - Latest Claude 4.1 Opus model
• vertex:claude-opus-4@20250514 - Claude 4 Opus model
• vertex:claude-sonnet-4@20250514 - Claude 4 Sonnet model
• vertex:claude-3-7-sonnet@20250219 - Claude 3.7 Sonnet model
• vertex:claude-3-haiku@20240307 - Fast Claude 3 Haiku
• vertex:claude-3-opus@20240229 - Claude 3 Opus (Public Preview)
• vertex:claude-3-5-haiku@20241022 - Claude 3.5 Haiku
• vertex:claude-3-5-sonnet-v2@20241022 - Claude 3.5 Sonnet

:::info Claude models require explicit access enablement through the Vertex AI Model Garden. Navigate to the Model Garden, search for "Claude", and enable the specific models you need. :::

Note: Claude models support up to 200,000 tokens context length and include built-in safety features.

Llama Models (Preview)

Meta's Llama models are available through Vertex AI with the following versions:

• vertex:llama4-scout-instruct-maas - Llama 4 Scout 17B (16 experts) with 10M context
• vertex:llama4-maverick-instruct-maas - Llama 4 Maverick 17B (128 experts) with 1M context
• vertex:llama-3.3-70b-instruct-maas - Latest Llama 3.3 70B model (Preview)
• vertex:llama-3.2-90b-vision-instruct-maas - Vision-capable Llama 3.2 90B (Preview)
• vertex:llama-3.1-405b-instruct-maas - Llama 3.1 405B (GA)
• vertex:llama-3.1-70b-instruct-maas - Llama 3.1 70B (Preview)
• vertex:llama-3.1-8b-instruct-maas - Llama 3.1 8B (Preview)

Note: Llama models support built-in safety features through Llama Guard. Llama 4 models support up to 10M tokens context length (Scout) and 1M tokens (Maverick) and are natively multimodal, supporting both text and image inputs.

Llama Configuration Example

providers:
  - id: vertex:llama-3.3-70b-instruct-maas
    config:
      region: us-central1 # Llama models are only available in this region
      temperature: 0.7
      maxOutputTokens: 1024
      llamaConfig:
        safetySettings:
          enabled: true # Llama Guard is enabled by default
          llama_guard_settings: {} # Optional custom settings

  - id: vertex:llama4-scout-instruct-maas
    config:
      region: us-central1
      temperature: 0.7
      maxOutputTokens: 2048
      llamaConfig:
        safetySettings:
          enabled: true

By default, Llama models use Llama Guard for content safety. You can disable it by setting enabled: false, but this is not recommended for production use.

Gemma Models (Open Models)

• vertex:gemma - Lightweight open text model for generation, summarization, and extraction
• vertex:codegemma - Lightweight code generation and completion model
• vertex:paligemma - Lightweight vision-language model for image tasks

PaLM 2 (Bison) Models

Please note the PaLM (Bison) models are scheduled for deprecation (April 2025) and it's recommended to migrate to the Gemini models.

• vertex:chat-bison[@001|@002] - Chat model
• vertex:chat-bison-32k[@001|@002] - Extended context chat
• vertex:codechat-bison[@001|@002] - Code-specialized chat
• vertex:codechat-bison-32k[@001|@002] - Extended context code chat
• vertex:text-bison[@001|@002] - Text completion
• vertex:text-unicorn[@001] - Specialized text model
• vertex:code-bison[@001|@002] - Code completion
• vertex:code-bison-32k[@001|@002] - Extended context code completion

Embedding Models

• vertex:textembedding-gecko@001 - Text embeddings (3,072 tokens, 768d)
• vertex:textembedding-gecko@002 - Text embeddings (2,048 tokens, 768d)
• vertex:textembedding-gecko@003 - Text embeddings (2,048 tokens, 768d)
• vertex:text-embedding-004 - Latest text embeddings (2,048 tokens, ≤768d)
• vertex:text-embedding-005 - Latest text embeddings (2,048 tokens, ≤768d)
• vertex:textembedding-gecko-multilingual@001 - Multilingual embeddings (2,048 tokens, 768d)
• vertex:text-multilingual-embedding-002 - Latest multilingual embeddings (2,048 tokens, ≤768d)
• vertex:multimodalembedding - Multimodal embeddings for text, image, and video

Image Generation Models

:::note Imagen models are available through Google AI Studio using the google:image: prefix. :::

Model Capabilities

Gemini 2.0 Pro Specifications

• Max input tokens: 2,097,152
• Max output tokens: 8,192
• Training data: Up to June 2024
• Supports: Text, code, images, audio, video, PDF inputs
• Features: System instructions, JSON support, grounding with Google Search

Language Support

Gemini models support a wide range of languages including:

• Core languages: Arabic, Bengali, Chinese (simplified/traditional), English, French, German, Hindi, Indonesian, Italian, Japanese, Korean, Portuguese, Russian, Spanish, Thai, Turkish, Vietnamese
• Gemini 1.5 adds support for 50+ additional languages including regional and less common languages

If you're using Google AI Studio directly, see the google provider documentation instead.

Setup and Authentication

1. Install Dependencies

Install Google's official auth client:

npm install google-auth-library

2. Enable API Access

1. Enable the Vertex AI API in your Google Cloud project

2. For Claude models, request access through the Vertex AI Model Garden by:

   • Navigating to "Model Garden"
   • Searching for "Claude"
   • Clicking "Enable" on the models you want to use

3. Set your project in gcloud CLI:

   gcloud config set project PROJECT_ID
   

3. Authentication Methods

Choose one of these authentication methods:

Option 1: Application Default Credentials (Recommended)

This is the most secure and flexible approach for development and production:

# First, authenticate with Google Cloud
gcloud auth login

# Then, set up application default credentials
gcloud auth application-default login

# Set your project ID
export VERTEX_PROJECT_ID="your-project-id"

Option 2: Service Account (Production)

For production environments or CI/CD pipelines:

1. Create a service account in your Google Cloud project
2. Download the credentials JSON file
3. Set the environment variable:

export GOOGLE_APPLICATION_CREDENTIALS="/path/to/credentials.json"
export VERTEX_PROJECT_ID="your-project-id"

Option 3: Service Account via Config (Alternative)

You can also provide service account credentials directly in your configuration:

providers:
  - id: vertex:gemini-2.5-pro
    config:
      # Load credentials from file
      credentials: 'file://service-account.json'
      projectId: 'your-project-id'

Or with inline credentials (not recommended for production):

providers:
  - id: vertex:gemini-2.5-pro
    config:
      credentials: '{"type":"service_account","project_id":"..."}'
      projectId: 'your-project-id'

This approach:

• Allows per-provider authentication
• Enables using different service accounts for different models
• Simplifies credential management in complex setups
• Avoids the need for environment variables

Option 4: Direct API Key (Quick Testing)

For quick testing, you can use a temporary access token:

# Get a temporary access token
export VERTEX_API_KEY=$(gcloud auth print-access-token)
# or use GEMINI_API_KEY
export GEMINI_API_KEY=$(gcloud auth print-access-token)
export VERTEX_PROJECT_ID="your-project-id"

Note: Access tokens expire after 1 hour. For long-running evaluations, use Application Default Credentials or Service Account authentication.

5. Environment Variables

Promptfoo automatically loads environment variables from your shell or a .env file. Create a .env file in your project root:

# .env
VERTEX_PROJECT_ID=your-project-id
VERTEX_REGION=us-central1
# Optional: For direct API key authentication
VERTEX_API_KEY=your-access-token
# or
GEMINI_API_KEY=your-access-token

Remember to add .env to your .gitignore file to prevent accidentally committing sensitive information.

Configuration

Environment Variables

The following environment variables can be used to configure the Vertex AI provider:

Variable	Description	Default	Required
VERTEX_PROJECT_ID	Your Google Cloud project ID	None	Yes
VERTEX_REGION	The region for Vertex AI resources	us-central1	No
VERTEX_API_KEY	Direct API token (from gcloud auth print-access-token)	None	No*
GEMINI_API_KEY	Alternative to VERTEX_API_KEY for API authentication	None	No*
VERTEX_PUBLISHER	Model publisher	google	No
VERTEX_API_HOST	Override API host (e.g., for proxy)	Auto-generated	No
VERTEX_API_VERSION	API version	v1	No
GOOGLE_APPLICATION_CREDENTIALS	Path to service account credentials	None	No*

*At least one authentication method is required (ADC, service account, or API key via VERTEX_API_KEY/GEMINI_API_KEY)

Region Selection

Different models are available in different regions. Common regions include:

• us-central1 - Default, most models available
• us-east4 - Additional capacity
• us-east5 - Claude models available
• europe-west1 - EU region, Claude models available
• europe-west4 - EU region
• asia-southeast1 - Asia region, Claude models available

Example configuration with specific region:

providers:
  - id: vertex:claude-3-5-sonnet-v2@20241022
    config:
      region: us-east5 # Claude models require specific regions
      projectId: my-project-id

Quick Start

1. Basic Setup

After completing authentication, create a simple evaluation:

# promptfooconfig.yaml
providers:
  - vertex:gemini-2.5-flash

prompts:
  - 'Analyze the sentiment of this text: {{text}}'

tests:
  - vars:
      text: "I love using Vertex AI, it's incredibly powerful!"
    assert:
      - type: contains
        value: 'positive'
  - vars:
      text: "The service is down and I can't access my models."
    assert:
      - type: contains
        value: 'negative'

Run the eval:

promptfoo eval

2. Multi-Model Comparison

Compare different models available on Vertex AI:

providers:
  # Google models
  - id: vertex:gemini-2.5-pro
    config:
      region: us-central1

  # Claude models (require specific region)
  - id: vertex:claude-3-5-sonnet-v2@20241022
    config:
      region: us-east5

  # Llama models
  - id: vertex:llama-3.3-70b-instruct-maas
    config:
      region: us-central1

prompts:
  - 'Write a Python function to {{task}}'

tests:
  - vars:
      task: 'calculate fibonacci numbers'
    assert:
      - type: javascript
        value: output.includes('def') && output.includes('fibonacci')
      - type: llm-rubric
        value: 'The code should be efficient and well-commented'

3. Using with CI/CD

For automated testing in CI/CD pipelines:

# .github/workflows/llm-test.yml
name: LLM Testing
on: [push]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: google-github-actions/auth@v2
        with:
          credentials_json: ${{ secrets.GCP_CREDENTIALS }}
      - name: Run promptfoo tests
        run: |
          npx promptfoo@latest eval
        env:
          VERTEX_PROJECT_ID: ${{ vars.GCP_PROJECT_ID }}
          VERTEX_REGION: us-central1

4. Advanced Configuration Example

providers:
  - id: vertex:gemini-2.5-pro
    config:
      # Authentication options
      credentials: 'file://service-account.json' # Optional: Use specific service account
      projectId: ${VERTEX_PROJECT_ID}
      region: ${VERTEX_REGION:-us-central1}

      generationConfig:
        temperature: 0.2
        maxOutputTokens: 2048
        topP: 0.95
      safetySettings:
        - category: HARM_CATEGORY_DANGEROUS_CONTENT
          threshold: BLOCK_ONLY_HIGH
      systemInstruction: |
        You are a helpful coding assistant.
        Always provide clean, efficient, and well-documented code.
        Follow best practices for the given programming language.

Provider Configuration

Configure model behavior using the following options:

providers:
  # For Gemini models
  - id: vertex:gemini-2.5-pro
    config:
      generationConfig:
        temperature: 0
        maxOutputTokens: 1024
        topP: 0.8
        topK: 40

  # For Llama models
  - id: vertex:llama-3.3-70b-instruct-maas
    config:
      generationConfig:
        temperature: 0.7
        maxOutputTokens: 1024
        extra_body:
          google:
            model_safety_settings:
              enabled: true
              llama_guard_settings: {}

  # For Claude models
  - id: vertex:claude-3-5-sonnet-v2@20241022
    config:
      anthropic_version: 'vertex-2023-10-16'
      max_tokens: 1024

Safety Settings

Control AI safety filters:

- id: vertex:gemini-pro
  config:
    safetySettings:
      - category: HARM_CATEGORY_HARASSMENT
        threshold: BLOCK_ONLY_HIGH
      - category: HARM_CATEGORY_VIOLENCE
        threshold: BLOCK_MEDIUM_AND_ABOVE

See Google's SafetySetting API documentation for details.

Model-Specific Features

Llama Model Features

• Support for text and vision tasks (Llama 3.2 and all Llama 4 models)
• Built-in safety with Llama Guard (enabled by default)
• Available in us-central1 region
• Quota limits vary by model version
• Requires specific endpoint format for API calls
• Only supports unary (non-streaming) responses in promptfoo

Llama Model Considerations

• Regional Availability: Llama models are available only in us-central1 region
• Guard Integration: All Llama models use Llama Guard for content safety by default
• Specific Endpoint: Uses a different API endpoint than other Vertex models
• Model Status: Most models are in Preview state, with Llama 3.1 405B being Generally Available (GA)
• Vision Support: Llama 3.2 90B and all Llama 4 models support image input

Claude Model Features

• Support for text, code, and analysis tasks
• Tool use (function calling) capabilities
• Available in multiple regions (us-east5, europe-west1, asia-southeast1)
• Quota limits vary by model version (20-245 QPM)

Advanced Usage

Default Grading Provider

When Google credentials are configured (and no OpenAI/Anthropic keys are present), Vertex AI becomes the default provider for:

• Model grading
• Suggestions
• Dataset generation

Override grading providers using defaultTest:

defaultTest:
  options:
    provider:
      # For llm-rubric and factuality assertions
      text: vertex:gemini-1.5-pro-002
      # For similarity comparisons
      embedding: vertex:embedding:text-embedding-004

Configuration Reference

Option	Description	Default
apiKey	GCloud API token	None
apiHost	API host override	{region}-aiplatform.googleapis.com
apiVersion	API version	v1
credentials	Service account credentials (JSON or file path)	None
projectId	GCloud project ID	VERTEX_PROJECT_ID env var
region	GCloud region	us-central1
publisher	Model publisher	google
context	Model context	None
examples	Few-shot examples	None
safetySettings	Content filtering	None
generationConfig.temperature	Randomness control	None
generationConfig.maxOutputTokens	Max tokens to generate	None
generationConfig.topP	Nucleus sampling	None
generationConfig.topK	Sampling diversity	None
generationConfig.stopSequences	Generation stop triggers	[]
toolConfig	Tool/function calling config	None
systemInstruction	System prompt (supports {{var}} and file://)	None

:::note Not all models support all parameters. See Google's documentation for model-specific details. :::

Troubleshooting

Authentication Errors

If you see an error like:

API call error: Error: {"error":"invalid_grant","error_description":"reauth related error (invalid_rapt)","error_uri":"https://support.google.com/a/answer/9368756","error_subtype":"invalid_rapt"}

Re-authenticate using:

gcloud auth application-default login

Claude Model Access Errors

If you encounter errors like:

API call error: Error: Project is not allowed to use Publisher Model `projects/.../publishers/anthropic/models/claude-*`

or

API call error: Error: Publisher Model is not servable in region us-central1

You need to:

1. Enable access to Claude models:

   • Visit the Vertex AI Model Garden
   • Search for "Claude"
   • Click "Enable" on the specific Claude models you want to use

2. Use a supported region. Claude models are only available in:

   • us-east5
   • europe-west1

Example configuration with correct region:

providers:
  - id: vertex:claude-3-5-sonnet-v2@20241022
    config:
      region: us-east5 # or europe-west1
      anthropic_version: 'vertex-2023-10-16'
      max_tokens: 1024

Model Features and Capabilities

Function Calling and Tools

Gemini and Claude models support function calling and tool use. Configure tools in your provider:

providers:
  - id: vertex:gemini-2.5-pro
    config:
      toolConfig:
        functionCallingConfig:
          mode: 'AUTO' # or "ANY", "NONE"
          allowedFunctionNames: ['get_weather', 'search_places']
      tools:
        - functionDeclarations:
            - name: 'get_weather'
              description: 'Get weather information'
              parameters:
                type: 'OBJECT'
                properties:
                  location:
                    type: 'STRING'
                    description: 'City name'
                required: ['location']

Tools can also be loaded from external files:

providers:
  - id: vertex:gemini-2.5-pro
    config:
      tools: 'file://tools.json' # Supports variable substitution

For practical examples of function calling with Vertex AI models, see the google-vertex-tools example which demonstrates both basic tool declarations and callback execution.

System Instructions

Configure system-level instructions for the model:

providers:
  - id: vertex:gemini-2.5-pro
    config:
      # Direct text
      systemInstruction: 'You are a helpful assistant'

      # Or load from file
      systemInstruction: file://system-instruction.txt

System instructions support Nunjucks templating and can be loaded from external files for better organization and reusability.

Generation Configuration

Fine-tune model behavior with these parameters:

providers:
  - id: vertex:gemini-2.5-pro
    config:
      generationConfig:
        temperature: 0.7 # Controls randomness (0.0 to 1.0)
        maxOutputTokens: 1024 # Limit response length
        topP: 0.8 # Nucleus sampling
        topK: 40 # Top-k sampling
        stopSequences: ["\n"] # Stop generation at specific sequences

Context and Examples

Provide context and few-shot examples:

providers:
  - id: vertex:gemini-2.5-pro
    config:
      context: 'You are an expert in machine learning'
      examples:
        - input: 'What is regression?'
          output: 'Regression is a statistical method...'

Safety Settings

Configure content filtering with granular control:

providers:
  - id: vertex:gemini-2.5-pro
    config:
      safetySettings:
        - category: 'HARM_CATEGORY_HARASSMENT'
          threshold: 'BLOCK_ONLY_HIGH'
        - category: 'HARM_CATEGORY_HATE_SPEECH'
          threshold: 'BLOCK_MEDIUM_AND_ABOVE'
        - category: 'HARM_CATEGORY_SEXUALLY_EXPLICIT'
          threshold: 'BLOCK_LOW_AND_ABOVE'

Thinking Configuration

For models that support thinking capabilities (like Gemini 2.5 Flash), you can configure the thinking budget:

providers:
  - id: vertex:gemini-2.5-flash
    config:
      generationConfig:
        temperature: 0.7
        maxOutputTokens: 2048
        thinkingConfig:
          thinkingBudget: 1024 # Controls tokens allocated for thinking process

The thinking configuration allows the model to show its reasoning process before providing the final answer. This is particularly useful for:

• Complex problem solving
• Mathematical reasoning
• Step-by-step analysis
• Decision making tasks

When using thinking configuration:

• The thinkingBudget must be at least 1024 tokens
• The budget is counted towards your total token usage
• The model will show its reasoning process in the response

Search Grounding

Search grounding allows Gemini models to access the internet for up-to-date information, enhancing responses about recent events and real-time data.

Basic Usage

Use the object format to enable Search grounding:

providers:
  - id: vertex:gemini-2.5-pro
    config:
      tools:
        - googleSearch: {}

Combining with Other Features

You can combine Search grounding with thinking capabilities for better reasoning:

providers:
  - id: vertex:gemini-2.5-flash
    config:
      generationConfig:
        thinkingConfig:
          thinkingBudget: 1024
      tools:
        - googleSearch: {}

Use Cases

Search grounding is particularly valuable for:

• Current events and news
• Recent developments
• Stock prices and market data
• Sports results
• Technical documentation updates

Working with Response Metadata

When using Search grounding, the API response includes additional metadata:

• groundingMetadata - Contains information about search results used
• groundingChunks - Web sources that informed the response
• webSearchQueries - Queries used to retrieve information

Requirements and Limitations

• Important: Per Google's requirements, applications using Search grounding must display Google Search Suggestions included in the API response metadata
• Search results may vary by region and time
• Results may be subject to Google Search rate limits
• Search will only be performed when the model determines it's necessary

For more details, see the Google documentation on Grounding with Google Search.

See Also

• Google AI Studio Provider - For direct Google AI Studio integration
• Vertex AI Examples - Browse working examples for Vertex AI
• Google Cloud Documentation - Official Vertex AI documentation
• Model Garden - Access and enable additional models