# Interface: FunctionTool

## Properties[​](#properties "Direct link to Properties")

### annotations?[​](#annotations "Direct link to annotations?")

```ts
optional annotations: ToolAnnotations;

```

Behavioural hints that drive the agents plugin's approval gate and the client's approval-card styling. Prefer setting `effect` (one of `"read" | "write" | "update" | "destructive"`) — any mutating value forces HITL approval before `execute()` runs. Legacy `destructive: true` is still honoured. Must be preserved through [functionToolToDefinition](./docs/api/appkit/Function.functionToolToDefinition.md) so the plugin sees them when building agent tool indexes.

***

### description?[​](#description "Direct link to description?")

```ts
optional description: string | null;

```

***

### execute()[​](#execute "Direct link to execute()")

```ts
execute: (args: Record<string, unknown>) => unknown;

```

Returns any shape; downstream `normalizeToolResult` serializes to a string before handing the value to the LLM.

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

| Parameter | Type                          |
| --------- | ----------------------------- |
| `args`    | `Record`<`string`, `unknown`> |

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

`unknown`

***

### name?[​](#name "Direct link to name?")

```ts
optional name: string;

```

Optional. When this tool is placed in a keyed record (`tools: { my_tool: ... }` or the function form), the agents plugin overrides this with the record key at index-build time. Only set it explicitly when constructing a `FunctionTool` outside any keyed-record context.

***

### parameters?[​](#parameters-1 "Direct link to parameters?")

```ts
optional parameters: Record<string, unknown> | null;

```

***

### strict?[​](#strict "Direct link to strict?")

```ts
optional strict: boolean | null;

```

***

### type[​](#type "Direct link to type")

```ts
type: "function";

```