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3737

3838Claude can interact with computer environments through the computer use tool, which provides screenshot capabilities and mouse/keyboard control for autonomous desktop interaction.

3939

40The computer use tool is an Anthropic-defined [client toolset](https://platform.claude.com/docs/en/agents-and-tools/tool-use/tool-reference#client-toolsets): one `{"type": "computer_toolset_20260801"}` entry in `tools` gives Claude 17 member tools such as `screenshot`, `left_click`, `type`, and `zoom`, and your application runs every call in an environment you control. It isn't currently available in [Claude Managed Agents](https://platform.claude.com/docs/en/managed-agents/tools). Claude's calls are `tool_use` blocks whose `name` is the member and which carry `"toolset_name": "computer"`, often several per turn (a [batch action](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#batch-actions)).

40The computer use tool is an Anthropic-defined [client toolset](https://platform.claude.com/docs/en/agents-and-tools/tool-use/tool-reference#client-toolsets): one `{"type": "computer_toolset_20260801"}` entry in `tools` gives Claude 17 member tools such as `screenshot`, `left_click`, `type`, and `zoom`, and your application runs every call in an environment you control. It isn't currently available in [Claude Managed Agents](https://platform.claude.com/docs/en/managed-agents/tools). Claude's calls are `tool_use` blocks whose `name` is the member and which carry `"toolset_name": "computer"`, often several in one turn (a [batch action](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#batch-actions)).

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4242For tasks that stay inside webpages, the [browser use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool) is the closer fit: its member tools read and act on the page itself, and it doesn't need a full desktop environment.

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6060 4. Asking a human to confirm decisions that might result in meaningful real-world consequences and any tasks requiring affirmative consent, such as accepting cookies, completing financial transactions, or agreeing to terms of service.

6161</Warning>

6262

63In some circumstances, Claude will follow commands found in content even when they conflict with your instructions. For example, instructions on webpages or contained in images might override your instructions or cause Claude to make mistakes. Take precautions to isolate Claude from sensitive data and actions to avoid risks related to prompt injection.

63In some circumstances, Claude follows commands found in content even when they conflict with your instructions. For example, instructions on webpages or contained in images might override your instructions or cause Claude to make mistakes. Take precautions to isolate Claude from sensitive data and actions to avoid risks related to prompt injection.

6464

6565Anthropic has trained the model to resist these prompt injections and has added an extra layer of defense. If you use the computer use tools, classifiers will automatically scan what the tools return, such as screenshots, to flag potential prompt injections. When these classifiers identify a potential prompt injection, they will automatically steer the model to check whether the instruction really came from you before acting on it.

6666

67This extra protection won't be ideal for every use case (for example, use cases without a human in the loop), so if you'd like to opt out and turn it off, [contact support](https://support.claude.com/en/). The precautions above remain important even with these classifiers in place.

67This extra protection isn't ideal for every use case (for example, use cases without a human in the loop), so if you'd like to opt out and turn it off, [contact support](https://support.claude.com/en/). The precautions listed earlier remain important even with these classifiers in place.

6868

6969Inform end users of relevant risks and obtain their consent prior to enabling computer use in your own products.

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275275 ```

276276</CodeGroup>

277277

278When Claude acts on the desktop, the response has a `stop_reason` of `tool_use` and contains one or more member `tool_use` blocks, each naming a member tool and carrying `"toolset_name": "computer"`. Partway through this task, after Claude has seen a screenshot of the desktop, a response might look like this:

278When Claude acts on the desktop, the response has a `stop_reason` of `tool_use` and contains one or more member `tool_use` blocks, each naming a member tool and carrying `"toolset_name": "computer"`. Partway through this task, after Claude has received a screenshot of the desktop, a response might look like this:

279279

280280```json Output

281281{

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308308}

309309```

310310

311Your application runs each call in order in your own environment, returns one `tool_result` block per `tool_use` block, and calls the API again; [How computer use works](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#how-computer-use-works) describes that loop, and the rest of this page shows how to implement it.

311Your application runs each call in order in your own environment, returns one `tool_result` block for each `tool_use` block, and calls the API again; [How computer use works](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#how-computer-use-works) describes that loop, and the rest of this page shows how to implement it.

312312

313313***

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328328

329329 <Step title="Run the calls in order and return results">

330330 * Iterate over every `tool_use` block in the response, in order. For each one, dispatch on the member `name` together with `toolset_name`, and perform that action with the block's `input` on your container or virtual machine.

331 * Continue the conversation with a new `user` message that contains one `tool_result` block per `tool_use` block, matched by `tool_use_id` and each echoing `"toolset_name": "computer"`. Return an image for `screenshot` and `zoom`; a short text such as `OK` is enough for the other actions.

331 * Continue the conversation with a new `user` message that contains one `tool_result` block for each `tool_use` block, matched by `tool_use_id` and each echoing `"toolset_name": "computer"`. Return an image for `screenshot` and `zoom`; a short text such as `OK` is enough for the other actions.

332332 * If an action fails, return `is_error: true` for that block and answer the rest of the batch as described in [Batch actions](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#batch-actions).

333333 </Step>

334334

335335 <Step title="Claude continues until the task is complete">

336336 * Claude analyzes the tool results to determine if more actions are needed or the task has been completed.

337 * If Claude determines more actions are needed, it responds with another `tool_use` `stop_reason` and you should return to step 3.

337 * If Claude determines more actions are needed, it responds with another `tool_use` `stop_reason`; return to step 3.

338338 * Otherwise, it returns a text response to the user.

339339 </Step>

340340</Steps>

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376376}

377377```

378378

379Return one `tool_result` block for each `tool_use` block, matched by `tool_use_id`, all in the next `user` message. Every result for a member tool must carry `"toolset_name": "computer"`; a result that omits it, or that names a different toolset than its `tool_use` block, is rejected. Only `screenshot` and `zoom` results need an image; for the other members, a short text acknowledgment such as `OK` is enough (`cursor_position` returns the coordinates as text):

379Return one `tool_result` block for each `tool_use` block, matched by `tool_use_id`, all in the next `user` message. Every result for a member tool must carry `"toolset_name": "computer"`; a result that omits it, or that names a different toolset from its `tool_use` block, is rejected. Only `screenshot` and `zoom` results need an image; for the other members, a short text acknowledgment such as `OK` is enough (`cursor_position` returns the coordinates as text):

380380

381381```json

382382{

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429429}

430430```

431431

432Claude then sees which actions succeeded, which one failed, and which were skipped, and replans on its next turn. A request that leaves any `tool_use` block in the batch unanswered is rejected with an `invalid_request_error`, so an agent loop that reads only the first block fails on its next call. If your application asks a human to confirm consequential actions, make that check before each block runs, because a batch can complete a multistep action within one turn.

432Claude then reads which actions succeeded, which one failed, and which were skipped, and replans on its next turn. A request that leaves any `tool_use` block in the batch unanswered is rejected with an `invalid_request_error`, so an agent loop that reads only the first block fails on its next call. If your application asks a human to confirm consequential actions, make that check before each block runs, because a batch can complete a multistep action within one turn.

433433

434Claude typically finishes a batch with `screenshot` so it can observe the outcome before determining what to do next. When a batch doesn't end with one, your application can attach a screenshot as an extra `image` block on the last result in the batch so that Claude always sees the current state of the screen, which saves a round trip compared with waiting for Claude to ask. You can also prompt Claude to end every batch with a screenshot (see [Optimize model performance with prompting](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#optimize-model-performance-with-prompting)).

434Claude typically finishes a batch with `screenshot` so it can observe the outcome before determining what to do next. When a batch doesn't end with one, your application can attach a screenshot as an extra `image` block on the last result in the batch so that Claude always receives the current state of the screen, which saves a round trip compared with waiting for Claude to ask. You can also prompt Claude to end every batch with a screenshot (see [Optimize model performance with prompting](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#optimize-model-performance-with-prompting)).

435435

436436### The computing environment

437437

438438Computer use requires a sandboxed computing environment where Claude can safely interact with applications and the web. This environment includes:

439439

4401. **Virtual display:** A virtual X11 display server (using Xvfb) that renders the desktop interface Claude will see through screenshots and control with mouse/keyboard actions.

4401. **Virtual display:** A virtual X11 display server (using Xvfb) that renders the desktop interface Claude sees through screenshots and controls with mouse/keyboard actions.

441441

4424422. **Desktop environment:** A lightweight UI with window manager (Mutter) and panel (Tint2) running on Linux, which provides a consistent graphical interface for Claude to interact with.

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468468

469469### Understand the agent loop

470470

471The core of computer use is the "agent loop": a cycle where Claude requests tool actions, your application runs them, and returns results to Claude. The loop uses the client you created in the [Quick start](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#quick-start), a `tools` array that declares only the computer use toolset, and the tool-call processing helper under [Implement the computer use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#implement-the-computer-use-tool). If you also declare other tools, such as the Quick start's bash and text editor tools, dispatch their `tool_use` blocks in the same pass; the helper answers only computer use member calls, and the loop treats a turn with no answered calls as finished. Here's a simplified example:

471The core of computer use is the "agent loop": a cycle where Claude requests tool actions, and your application runs them and returns results to Claude. The loop uses the client you created in the [Quick start](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#quick-start), a `tools` array that declares only the computer use toolset, and the tool-call processing helper under [Implement the computer use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#implement-the-computer-use-tool). If you also declare other tools, such as the Quick start's bash and text editor tools, dispatch their `tool_use` blocks in the same pass; the helper answers only computer use member calls, and the loop treats a turn with no answered calls as complete. Here's a simplified example:

472472

473473<CodeGroup exclude="shell">

474474 ```python Python

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862862}

863863```

864864

865If your agent loop can run only one action per round trip, set `disable_parallel_tool_use` to `true` in `tool_choice`; Claude then returns at most one member `tool_use` block per turn (see [Disable parallel tool use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/parallel-tool-use#disable-parallel-tool-use)).

865If your agent loop can run only one action for each round trip, set `disable_parallel_tool_use` to `true` in `tool_choice`; Claude then returns at most one member `tool_use` block for each turn (see [Disable parallel tool use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/parallel-tool-use#disable-parallel-tool-use)).

866866

867867The entry rejects these parameters from earlier tool versions, and a request that includes any of them returns an `invalid_request_error`:

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15651565 </Step>

15661566

15671567 <Step title="Implement the agent loop">

1568 Wrap the two previous steps in a loop that sends the results back and repeats until Claude returns no member tool calls; [Understand the agent loop](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#understanding-the-agentic-loop) shows this loop in each language.

15691569 </Step>

15701570</Steps>

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15941594

15951595### Size screenshots to fit image limits

15961596

1597Screenshots and zoom images that you return to the computer use toolset must already fit within your model's [image size limits](https://platform.claude.com/docs/en/build-with-claude/vision#evaluate-image-size): the toolset takes no display dimensions and the API doesn't downscale for you, so an oversized `tool_result` image is rejected with a validation error. Because Claude returns coordinates in the pixel space of the image it sees, keep the scale factor you used so you can map those coordinates back to your screen.

1597Screenshots and zoom images that you return to the computer use toolset must already fit within your model's [image size limits](https://platform.claude.com/docs/en/build-with-claude/vision#evaluate-image-size): the toolset takes no display dimensions and the API doesn't downscale for you, so an oversized `tool_result` image is rejected with a validation error. Because Claude returns coordinates in the pixel space of the image it receives, keep the scale factor you used so you can map those coordinates back to your screen.

15981598

15991599<Note>

1600 Limits vary by model. Claude Opus 4.7 and later models, including every model that supports `computer_toolset_20260801`, accept up to 2576 pixels on the long edge and 4784 visual tokens total (`⌈width / 28⌉ × ⌈height / 28⌉`, approximately 3.75 megapixels); earlier models accept up to 1568 pixels on the long edge and approximately 1.15 megapixels total (see [Resolution and token cost](https://platform.claude.com/docs/en/build-with-claude/vision#evaluate-image-size) for each model's tier). The following example uses the earlier-model 1568 px / 1.15 MP limits. For a high-resolution-tier model, size to the visual-token limit rather than a pixel total, for example with the resize helper in [Resize your image before uploading](https://platform.claude.com/docs/en/build-with-claude/vision-coordinates#resize-your-image-before-uploading).

1600 Limits vary by model. Claude Opus 4.7 and later models, including every model that supports `computer_toolset_20260801`, accept up to 2576 pixels on the long edge and 4,784 visual tokens total (`⌈width / 28⌉ × ⌈height / 28⌉`, approximately 3.75 megapixels); earlier models accept up to 1568 pixels on the long edge and approximately 1.15 megapixels total (see [Resolution and token cost](https://platform.claude.com/docs/en/build-with-claude/vision#evaluate-image-size) for each model's tier). The following example uses the earlier-model 1568 px / 1.15 MP limits. For a high-resolution-tier model, size to the visual-token limit rather than a pixel total, for example with the resize helper in [Resize your image before uploading](https://platform.claude.com/docs/en/build-with-claude/vision-coordinates#resize-your-image-before-uploading).

16011601</Note>

16021602

16031603If your screen is larger than the limit, resize each screenshot before returning it and scale Claude's returned coordinates back to the original screen space. Because the toolset takes no display dimensions, the resize and the coordinate scaling in your application code are all you need:

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18161816

18171817To keep [Prompt caching](https://platform.claude.com/docs/en/build-with-claude/prompt-caching) effective while bounding context:

18181818

1819* Place one `cache_control` breakpoint after the system prompt and tool definitions, and up to three more on the last `tool_result` block of each of the most recent turns, advancing them each turn. Within a [batch action](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#batch-actions), markers on several blocks act as a single breakpoint but each still counts toward the limit of four, so use one per turn.

18201820* Prune old screenshots in *batches*, not one each turn. Dropping a screenshot every turn changes the prefix every turn and invalidates the cache. A reasonable default is to keep the last three screenshots and prune every 25 turns, so the prefix stays byte-identical between prune events; if your screenshots exceed 2000 px on either side, choose an interval that keeps each request at 20 or fewer images.

18211821* On Claude Fable 5.1, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5, avoid pruning on the client: removing an earlier screenshot [invalidates every later thinking block](https://platform.claude.com/docs/en/build-with-claude/thinking#preserved-in-conversation) in every request that still carries those turns. Resize screenshots to 2000 px or less per side instead, and use server-side [tool result clearing](https://platform.claude.com/docs/en/build-with-claude/context-editing#tool-result-clearing) to drop old ones from the context. If you must prune, keep [`prefix_mismatch_behavior: "drop_block"`](https://platform.claude.com/docs/en/build-with-claude/thinking#preserved-thinking-controls) set from then on; after each prune, Claude continues without the thinking produced since the pruned screenshot, on that request and every later one. On Claude Sonnet 5.5, `block_binding` works only with `thinking: {"type": "adaptive"}`. With `between_tools`, keep the history append-only, or strip the thinking blocks from the edited turn on. On Claude Haiku 5.5, `block_binding` works only with `thinking: {"type": "adaptive"}`; with `thinking: {"type": "disabled"}`, keep the history append-only, or strip the thinking blocks from the edited turn on.

18221822

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211121112. **Change the `tools` entry.** Set `type` to `computer_toolset_20260801` and delete `name`, `display_width_px`, `display_height_px`, `display_number`, and `enable_zoom`. The toolset rejects each of these fields.

211221123. **Choose whether to keep zoom enabled.** Zoom is enabled by default on the toolset, whereas `enable_zoom` defaults to `false`. If your environment doesn't implement zoom, add `"configs": {"zoom": {"enabled": false}}` to keep the previous behavior; otherwise implement it (see [Available actions](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#available-actions)).

211321134. **Handle every block in a turn.** Update your agent loop to iterate over every `tool_use` block in a response rather than reading only the first, and to dispatch on the block's `name` together with `toolset_name` instead of on `input.action`. Member inputs no longer contain an `action` field; the remaining fields are unchanged.

21145. **Run blocks in order and use the halt text.** Run the blocks sequentially, stop at the first failure, and answer the remaining blocks with `Not executed: an earlier computer action in this turn failed.` as described in [Batch actions](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#batch-actions). If your loop can't run batches yet, [Tool parameters](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#tool-parameters) explains how to limit Claude to one action per turn.

211521156. **Echo `toolset_name` on results.** Add `"toolset_name": "computer"` to every `tool_result` that answers a member call. Results may contain only `text` and `image` content.

211621167. **Support `repeat` on `key`.** The `key` member accepts an optional `repeat` count from 1 to 100. A handler that ignores unrecognized fields would press the key once, so make your `key` handler honor `repeat`.

211721178. **Resize screenshots yourself.** The toolset rejects a screenshot or zoom image that exceeds the model's image limits instead of downscaling it. Resize before returning the image and keep scaling coordinates as described in [Size screenshots to fit image limits](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#handle-coordinate-scaling-for-higher-resolutions).

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22272227 </Card>

22282228

22292229 <Card title="Tool use with Claude" icon="tool" href="https://platform.claude.com/docs/en/agents-and-tools/tool-use/overview">

2230 Connect Claude to external tools and APIs. See where tools execute, when Claude calls them, and which tool fits your task.

2230 Connect Claude to external tools and APIs. See where tools run, when Claude calls them, and which tool fits your task.

22312231 </Card>

22322232

22332233 <Card title="Best practices in detail" icon="book" href="https://claude.com/blog/best-practices-for-computer-and-browser-use-with-claude">

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