scroll · Mcp Desktop MCP: Risk & Policy

WHAT IT DOES

What scroll does on Mcp Desktop

AI agents invoke scroll to trigger actions in Mcp Desktop. 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.

WHY IT NEEDS A POLICY

Why scroll needs a policy

Scrolling is an active UI control action that sends input events to the frontmost application. While scrolling itself doesn't create or delete data, it executes a UI operation that can trigger side effects depending on the target application (e.g., loading new content, activating UI elements). It falls under Execute as it performs an external operation whose effects depend on arguments (coordinates and target app).

From the tool's definition "Scroll at the given screen coordinates" — triggers a UI interaction (scroll event) at specified coordinates on the desktop

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

scroll Rate-limited

scroll 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "scroll": {
      "limits": [
        {
          "counter": "scroll_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Mcp Desktop, so you can run agents against it safely.

FAQ

Questions about scroll

What does the scroll tool do? +

Scroll at the given screen coordinates. Pass verify_app to confirm the right app is frontmost first. It is categorised as a Execute tool in the Mcp Desktop MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on scroll? +

Register the Mcp Desktop MCP server in PolicyLayer and add a rule for scroll: 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 Mcp Desktop. Nothing to install.

What risk level is scroll? +

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

Can I rate-limit scroll? +

Yes. Add a rate_limit block to the scroll 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 scroll completely? +

Set action: deny in the PolicyLayer policy for scroll. 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 scroll? +

scroll is provided by the Mcp Desktop MCP server (mocha06/mcp-desktop). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.