# Dynamic Tools Demo
Demonstrates Genkit's dynamic tool creation (`ai.dynamic_tool()`) and
sub-span tracing (`ai.run()`). These features let you create tools at
runtime and wrap arbitrary functions as traceable steps.
## Quick Start
```bash
export GEMINI_API_KEY=your-api-key
./run.sh
```
Then open the Dev UI at http://localhost:4000.
## Flows
| Flow | What It Demonstrates |
|------|---------------------|
| `dynamic_tool_demo` | Creates a tool at runtime with `ai.dynamic_tool()` and calls it |
| `run_step_demo` | Wraps a plain function as a traceable step with `ai.run()` |
| `combined_demo` | Uses both `ai.run()` and `ai.dynamic_tool()` together |
## Key APIs
- **`ai.dynamic_tool(name, fn, description=...)`** -- Creates a tool that is NOT globally
registered. Useful for one-off tools or tools generated from user input.
- **`ai.run(name, input, fn)`** -- Wraps a function call as a named step in the
trace. The step appears in the Dev UI trace viewer.
## Development
The `run.sh` script uses `watchmedo` for hot reloading on file changes.
