Vertex AI Thinking

Enable extended thinking with a 1024-token budget on Claude Sonnet 4 via Vertex AI.

The source uses claude-sonnet-4@20250514, which Anthropic lists as deprecated on Google Cloud. Google's Sonnet 4 card does not establish a completed retirement. For a new deployment, choose a current model and its supported settings, such as Sonnet 4.6. Provider availability and lifecycle dates can differ from the direct Anthropic API.

thinking.py
"""
Vertexai Thinking
=================

Cookbook example for `vertexai/claude/thinking.py`.
"""

from agno.agent import Agent
from agno.models.vertexai.claude import Claude

# ---------------------------------------------------------------------------
# Create Agent
# ---------------------------------------------------------------------------

agent = Agent(
    model=Claude(
        id="claude-sonnet-4@20250514",
        max_tokens=2048,
        thinking={"type": "enabled", "budget_tokens": 1024},
    ),
    markdown=True,
)

# Print the response in the terminal

# ---------------------------------------------------------------------------
# Run Agent
# ---------------------------------------------------------------------------
if __name__ == "__main__":
    # --- Sync ---
    agent.print_response("Share a very scary 2 sentence horror story")

    # --- Sync + Streaming ---
    agent.print_response("Share a very scary 2 sentence horror story", stream=True)

Run the Example

Set up your virtual environment

uv venv --python 3.12
source .venv/bin/activate

Install dependencies

uv pip install -U agno "anthropic[vertex]"

Set up Google Cloud access

Use a project with billing and aiplatform.googleapis.com enabled, enable the chosen Claude model in Model Garden, and give your calling identity permission to use it. Follow Google's Claude setup guide. Install the Google Cloud CLI for the local sign-in command below.

Set the project and a location supported by your model. us-east5 is a supported example for Sonnet 4 and Sonnet 4.6; check the model's current availability before switching models or locations.

export ANTHROPIC_VERTEX_PROJECT_ID="your-project-id"
export CLOUD_ML_REGION="us-east5"

Authenticate locally with Application Default Credentials:

gcloud auth application-default login

ADC supplies credentials; it does not enable models or grant IAM permissions. These examples authenticate to Google Cloud without an Anthropic API key.

Run the example

Save the code above as thinking.py, then run:

python thinking.py

Full source: cookbook/90_models/vertexai/claude/thinking.py