***

title: purpose
slug: /reference/typescript/agents/data-map/purpose
description: Set the function description shown to the AI.
max-toc-depth: 3
---------------------

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[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**

<ParamField path="description" type="string" required={true} toc={true}>
  Human-readable description of what this function does.
</ParamField>

## **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');
```