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basic_fallback.py
"""
Fallback Models — Basic
=============================

When the primary model fails (after exhausting its own retries),
fallback models are tried in order until one succeeds.
"""

from agno.agent import Agent
from agno.models.anthropic import Claude
from agno.models.openai import OpenAIChat

# ---------------------------------------------------------------------------
# Basic: pass a list of fallback models directly
# The primary model points to an unreachable server so it will fail
# with a connection error, then the fallback (Claude) handles the request.
# ---------------------------------------------------------------------------
agent = Agent(
    model=OpenAIChat(id="gpt-4o", base_url="http://localhost:1/v1", retries=0),
    fallback_models=[Claude(id="claude-sonnet-4-20250514")],
)

# ---------------------------------------------------------------------------
# Run Agent
# ---------------------------------------------------------------------------
if __name__ == "__main__":
    agent.print_response("What is the meaning of life?", stream=True)

​
Run the Example

1

Set up your virtual environment

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

uv venv --python 3.12
.venv\Scripts\activate
2

Install dependencies

uv pip install -U agno anthropic openai
3

Export your API keys

export ANTHROPIC_API_KEY="your_anthropic_api_key_here"
export OPENAI_API_KEY="your_openai_api_key_here"

$Env:ANTHROPIC_API_KEY="your_anthropic_api_key_here"
$Env:OPENAI_API_KEY="your_openai_api_key_here"
4

Run the example

Save the code above as basic_fallback.py, then run:
python basic_fallback.py
Full source: cookbook/02_agents/17_fallback_models/01_basic_fallback.py