send_key · Mcp Serial Hid Kvm MCP: Risk & Policy

WHAT IT DOES

What send_key does on Mcp Serial Hid Kvm

AI agents invoke send_key to trigger actions in Mcp Serial Hid Kvm. 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 send_key needs a policy

This tool executes keyboard input on a remote physical machine. While a single key press seems innocuous, the ability to send arbitrary key combinations (e.g., Alt+F4, Ctrl+Alt+Del, or destructive shortcuts) to a physical PC constitutes execution of external operations.

From the tool's definition 'Send a single key press with optional modifier keys (e.g., Ctrl+C, Alt+F4)' — triggers external keyboard input operations on a physical PC

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

send_key Rate-limited

send_key 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": {
    "send_key": {
      "limits": [
        {
          "counter": "send_key_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 Serial Hid Kvm, so you can run agents against it safely.

FAQ

Questions about send_key

What does the send_key tool do? +

Send a single key press with optional modifier keys (e.g., Ctrl+C, Alt+F4). It is categorised as a Execute tool in the Mcp Serial Hid Kvm MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on send_key? +

Register the Mcp Serial Hid Kvm MCP server in PolicyLayer and add a rule for send_key: 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 Serial Hid Kvm. Nothing to install.

What risk level is send_key? +

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

Can I rate-limit send_key? +

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

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

send_key is provided by the Mcp Serial Hid Kvm MCP server (sunasaji/mcp-serial-hid-kvm). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.