alarm_control · Homeassistant MCP: Risk & Policy

WHAT IT DOES

What alarm_control does on Homeassistant

AI agents invoke alarm_control to trigger actions in Homeassistant. 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 alarm_control needs a policy

The description is empty, so classification relies solely on the tool name. 'alarm_control' on a Home Assistant server most likely controls a security alarm system (arm/disarm/trigger), which is an external operation with significant real-world consequences. This falls under Execute (triggering external operations). Severity is high because misuse could disable home security or trigger false alarms.

From the tool's definition Tool name 'alarm_control' on a Home Assistant MCP server that enables AI assistants to control devices and services.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

alarm_control Rate-limited

alarm_control 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": {
    "alarm_control": {
      "limits": [
        {
          "counter": "alarm_control_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 Homeassistant, so you can run agents against it safely.

FAQ

Questions about alarm_control

What does the alarm_control tool do? +

alarm_control. It is categorised as a Execute tool in the Homeassistant MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on alarm_control? +

Register the Homeassistant MCP server in PolicyLayer and add a rule for alarm_control: 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 Homeassistant. Nothing to install.

What risk level is alarm_control? +

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

Can I rate-limit alarm_control? +

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

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

alarm_control is provided by the Homeassistant MCP server (robbrad/homeassistant-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.