> Fetch clean Markdown by appending `.md` to any page URL under https://signalwire.com/docs or requesting it with the HTTP header `Accept: text/markdown`. The root index at https://signalwire.com/docs/llms.txt lists the available documentation indexes.

# purpose

> Set the function description shown to the AI.

[ref-datamap]: /docs/server-sdks/reference/typescript/agents/data-map

[description]: /docs/server-sdks/reference/typescript/agents/data-map/description

Set the function description shown to the AI when deciding which tool to call.
[`description()`][description] is an alias for this method.

## **Parameters**

**`description`** `string` — required

Human-readable description of what this function does.

---

## **Returns**

[`DataMap`][ref-datamap] -- Self for method chaining.

## **Example**

```typescript {4}
import { DataMap } from '@signalwire/sdk';

const dm = new DataMap('get_weather');
dm.purpose('Look up current weather for a city');
```

> Set the function description shown to the AI.