Tool Use

Use web search tools with Claude Sonnet 4.6 through a local Nexus gateway.

The source routes requests to Anthropic's retired claude-sonnet-4-20250514 model. Replace it with anthropic/claude-sonnet-4-6 before running. See Anthropic model deprecations.

tool_use.py
"""Run `uv pip install ddgs` to install dependencies."""

import asyncio

from agno.agent import Agent
from agno.models.nexus import Nexus
from agno.tools.websearch import WebSearchTools

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

agent = Agent(
    model=Nexus(id="anthropic/claude-sonnet-4-20250514"),
    tools=[WebSearchTools()],
    markdown=True,
)

# ---------------------------------------------------------------------------
# Run Agent
# ---------------------------------------------------------------------------
if __name__ == "__main__":
    # --- Sync ---
    agent.print_response("Whats happening in France?")

    # --- Sync + Streaming ---
    agent.print_response("Whats happening in France?", stream=True)

    # --- Async ---
    asyncio.run(agent.aprint_response("Whats happening in France?"))

    # --- Async + Streaming ---
    asyncio.run(agent.aprint_response("Whats happening in France?", stream=True))

Run the Example

Configure the gateway in the first terminal

Install Nexus. Create nexus.toml with this loopback-only configuration:

nexus.toml
[server]
listen_address = "127.0.0.1:8000"

[llm]
enabled = true

[llm.protocols.openai]
enabled = true
path = "/llm"

[llm.providers.anthropic]
type = "anthropic"
api_key = "{{ env.ANTHROPIC_API_KEY }}"

[llm.providers.anthropic.models."claude-sonnet-4-6"]

Start the gateway in the first terminal

Set an Anthropic API key with access to Sonnet 4.6. The gateway process uses this key for upstream model requests.

export ANTHROPIC_API_KEY="your_anthropic_api_key_here"

From the directory containing nexus.toml, run nexus. Leave this foreground process running and open a second terminal in your example directory for the remaining steps.

Set up your virtual environment

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

Install the client dependencies in the second terminal

uv pip install -U agno openai ddgs

Configure the current client model

Replace anthropic/claude-sonnet-4-20250514 with anthropic/claude-sonnet-4-6 and add api_key="nexus-local" to Nexus(...) in the saved file. The default URL matches this gateway's http://localhost:8000/llm/v1/ route.

This TOML does not enable client OAuth. The nonempty dummy bearer satisfies the OpenAI SDK; it is not an OpenAI provider key and does not secure the gateway. An OAuth-protected deployment instead needs its required client access token. The Anthropic provider key remains in the gateway terminal.

Run the example in the second terminal

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

python tool_use.py

Full source: cookbook/90_models/nexus/tool_use.py