High Risk →

prompt

Control the computer with natural language using an AI agent.

How to control prompt ↓

What prompt does on Computer Use

AI agents invoke prompt to trigger actions in Computer Use. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

High Risk

Why prompt needs a policy

This tool is an AI agent that can perform any computer operation via natural language prompts. It is a meta-tool that can invoke all sibling tools (execute_bash, restart_computer, double_click, etc.), meaning it can read, write, execute code, delete files, and potentially perform financial transactions.

From the tool's definition 'Control the computer with natural language using an AI agent' - this tool executes arbitrary computer actions driven by natural language instructions, encompassing all possible operations including destructive and financial ones

Documented attack patterns abuse exactly the kind of access prompt gives an agent:

How to control prompt

PolicyLayer is an MCP gateway — it sits between your AI agents and Computer Use, and nothing reaches the server without passing your rules. This is the rule we recommend for prompt:

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "prompt": {
      "limits": [
        {
          "counter": "prompt_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

prompt stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

  1. Create a free account and register Computer Use — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
RATE-LIMIT THIS TOOL →

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Related tools and policies

Go deeper

Questions about prompt

What does the prompt tool do? +

Control the computer with natural language using an AI agent. It is categorised as a Execute tool in the Computer Use MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on prompt? +

Register the Computer Use MCP server in PolicyLayer and add a rule for prompt: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Computer Use. Nothing to install.

What risk level is prompt? +

prompt is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit prompt? +

Yes. Add a rate_limit block to the prompt rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block prompt completely? +

Set action: deny in the PolicyLayer policy for prompt. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides prompt? +

prompt is provided by the Computer Use MCP server (spencerkinney/computer-use-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Computer Use tool call.

Start from Computer Use, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

Free to start. No card required.

15 Computer Use tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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