Frontend Tools Setup - Copilotkit

<Steps> <Step> ### Nothing to wire on the agent

The AG-UI protocol forwards frontend tool definitions to the agent at
request time, so the backend agent declares no bespoke tools. The LLM sees
a component registered with `useComponent` through the AG-UI request payload
and picks it when the user asks for what it draws.

```python title="src/agents/chart_agent.py"
from llama_index.llms.openai import OpenAI

llm = OpenAI(model="gpt-4.1-mini")
```

</Step> <Step> ### Tell the model when to call it

The tool arrives on every run, but a model with no instruction about it will
answer in prose instead of calling it. Name the tool in the system prompt.

```python title="src/agents/chart_agent.py"
SYSTEM_PROMPT = """You are a data visualization assistant.

When the user asks for a chart, call `render_bar_chart` with a concise
title and a `data` array of `{label, value}` items."""
```

</Step> </Steps>