vnc_key_tap · VNC MCP Server MCP: Risk & Policy

WHAT IT DOES

What vnc_key_tap does on VNC MCP Server

AI agents invoke vnc_key_tap to trigger actions in VNC MCP Server. 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 vnc_key_tap needs a policy

Sending keystrokes to a remote computer is an Execute-level action: it triggers external operations (keypresses) whose effects entirely depend on the current state of the remote system and what keys are sent. Misuse could trigger arbitrary actions (e.g., Enter to confirm dialogs, shortcuts to delete files, or keyboard shortcuts for financial transactions).

From the tool's definition 'Tap a key' — triggers keyboard input on a remote computer via VNC, performing direct input control on the target system

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

vnc_key_tap Rate-limited

vnc_key_tap 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": {
    "vnc_key_tap": {
      "limits": [
        {
          "counter": "vnc_key_tap_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 VNC MCP Server, so you can run agents against it safely.

FAQ

Questions about vnc_key_tap

What does the vnc_key_tap tool do? +

Tap a key (e.g.,. It is categorised as a Execute tool in the VNC MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on vnc_key_tap? +

Register the VNC MCP Server MCP server in PolicyLayer and add a rule for vnc_key_tap: 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 VNC MCP Server. Nothing to install.

What risk level is vnc_key_tap? +

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

Can I rate-limit vnc_key_tap? +

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

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

vnc_key_tap is provided by the VNC MCP Server MCP server (volkan-m/vnc-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.