# `filterActiveTools()`

<Note type="warning">`filterActiveTools` is an experimental feature.</Note>

`filterActiveTools` filters a tool set to only the string tool names listed in `activeTools`.
If `activeTools` is `undefined`, it returns the original tool set.
If `tools` is `undefined`, it returns `undefined`.

`filterActiveTools` is useful for limiting which tools are sent to a model in a particular step.

```ts
import { experimental_filterActiveTools as filterActiveTools, tool } from 'ai';
import { z } from 'zod';

const tools = {
  weather: tool({
    description: 'Get the weather for a city',
    inputSchema: z.object({ city: z.string() }),
  }),
  time: tool({
    description: 'Get the current time for a city',
    inputSchema: z.object({ city: z.string() }),
  }),
};

const activeTools = ['weather'] as const;

const filteredTools = filterActiveTools({
  tools,
  activeTools,
});
```

## Import

<Snippet
  text={`import { experimental_filterActiveTools as filterActiveTools } from "ai"`}
  prompt={false}
/>

## API Signature

### Parameters

<PropertiesTable
  content={[
    {
      name: 'tools',
      type: 'ToolSet | undefined',
      description: 'The tool set to filter.',
    },
    {
      name: 'activeTools',
      type: 'ActiveTools<TOOLS>',
      description:
        'The names of the tools that should remain active. When omitted, all tools are returned.',
    },
  ]}
/>

### Returns

The filtered tool set, or `undefined` when `tools` is `undefined`.

When `activeTools` is provided as a literal array such as `["weather"] as const`,
TypeScript narrows the return type to only that subset of tools.

## Types

### `ActiveTools`

```ts
type ActiveTools<TOOLS extends ToolSet> =
  | ReadonlyArray<keyof TOOLS & string>
  | undefined;
```

`ActiveTools` only accepts string keys from the tool set because tool names are strings at runtime.


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- [createMCPClient](/docs/reference/ai-sdk-core/create-mcp-client)
- [experimental_getRealtimeToolDefinitions](/docs/reference/ai-sdk-core/get-realtime-tool-definitions)
- [MCP Apps](/docs/reference/ai-sdk-core/mcp-apps)
- [Experimental_StdioMCPTransport](/docs/reference/ai-sdk-core/mcp-stdio-transport)
- [jsonSchema](/docs/reference/ai-sdk-core/json-schema)
- [zodSchema](/docs/reference/ai-sdk-core/zod-schema)
- [valibotSchema](/docs/reference/ai-sdk-core/valibot-schema)
- [Output](/docs/reference/ai-sdk-core/output)
- [filterActiveTools](/docs/reference/ai-sdk-core/filter-active-tools)
- [ModelMessage](/docs/reference/ai-sdk-core/model-message)
- [UIMessage](/docs/reference/ai-sdk-core/ui-message)
- [validateUIMessages](/docs/reference/ai-sdk-core/validate-ui-messages)
- [safeValidateUIMessages](/docs/reference/ai-sdk-core/safe-validate-ui-messages)
- [Experimental_SandboxSession](/docs/reference/ai-sdk-core/sandbox)
- [createProviderRegistry](/docs/reference/ai-sdk-core/provider-registry)
- [customProvider](/docs/reference/ai-sdk-core/custom-provider)
- [cosineSimilarity](/docs/reference/ai-sdk-core/cosine-similarity)
- [wrapLanguageModel](/docs/reference/ai-sdk-core/wrap-language-model)
- [wrapImageModel](/docs/reference/ai-sdk-core/wrap-image-model)
- [LanguageModelV4Middleware](/docs/reference/ai-sdk-core/language-model-v2-middleware)
- [extractReasoningMiddleware](/docs/reference/ai-sdk-core/extract-reasoning-middleware)
- [simulateStreamingMiddleware](/docs/reference/ai-sdk-core/simulate-streaming-middleware)
- [defaultSettingsMiddleware](/docs/reference/ai-sdk-core/default-settings-middleware)
- [addToolInputExamplesMiddleware](/docs/reference/ai-sdk-core/add-tool-input-examples-middleware)
- [extractJsonMiddleware](/docs/reference/ai-sdk-core/extract-json-middleware)
- [isStepCount](/docs/reference/ai-sdk-core/is-step-count)
- [hasToolCall](/docs/reference/ai-sdk-core/has-tool-call)
- [isLoopFinished](/docs/reference/ai-sdk-core/loop-finished)
- [simulateReadableStream](/docs/reference/ai-sdk-core/simulate-readable-stream)
- [smoothStream](/docs/reference/ai-sdk-core/smooth-stream)
- [generateId](/docs/reference/ai-sdk-core/generate-id)
- [createIdGenerator](/docs/reference/ai-sdk-core/create-id-generator)
- [DefaultGeneratedFile](/docs/reference/ai-sdk-core/default-generated-file)


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