# Function: defineTool()

```ts
function defineTool<S>(config: ToolEntry<S>): ToolEntry<S>;

```

Defines a single tool entry for a plugin's internal registry.

The generic `S` flows from `schema` through to the `handler` callback so `args` is fully typed from the Zod schema. Names are assigned by the registry key, so they are not repeated inside the entry.

## Type Parameters[​](#type-parameters "Direct link to Type Parameters")

| Type Parameter                                                                           |
| ---------------------------------------------------------------------------------------- |
| `S` *extends* `ZodType`<`unknown`, `unknown`, `$ZodTypeInternals`<`unknown`, `unknown`>> |

## Parameters[​](#parameters "Direct link to Parameters")

| Parameter | Type                                                               |
| --------- | ------------------------------------------------------------------ |
| `config`  | [`ToolEntry`](./docs/api/appkit/Interface.ToolEntry.md)<`S`> |

## Returns[​](#returns "Direct link to Returns")

[`ToolEntry`](./docs/api/appkit/Interface.ToolEntry.md)<`S`>