set_temp_setpoint · Home Controller MCP: Risk & Policy

WHAT IT DOES

What set_temp_setpoint does on Home Controller

AI agents use set_temp_setpoint to create or update resources in Home Controller — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Home Controller environment.

WHY IT NEEDS A POLICY

Why set_temp_setpoint needs a policy

This tool writes a configuration value (temperature setpoint) to a smart home device. It is reversible (the temperature can be changed again), so it falls under Write rather than Destructive. Misuse could cause discomfort or minor safety issues (e.g., setting sauna or HVAC to extreme temperatures), warranting medium severity.

From the tool's definition 'Set temperature setpoint in °C (e.g. 21.5)' — modifies a device's target temperature setting

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_temp_setpoint Rate-limited

set_temp_setpoint stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_temp_setpoint": {
      "limits": [
        {
          "counter": "set_temp_setpoint_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about set_temp_setpoint

What does the set_temp_setpoint tool do? +

Set temperature setpoint in °C (e.g. 21.5). It is categorised as a Write tool in the Home Controller MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_temp_setpoint? +

Register the Home Controller MCP server in PolicyLayer and add a rule for set_temp_setpoint: 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 Home Controller. Nothing to install.

What risk level is set_temp_setpoint? +

set_temp_setpoint is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit set_temp_setpoint? +

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

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

set_temp_setpoint is provided by the Home Controller MCP server (winsthuang/home-controller). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.