update_device_property · HC3 MCP Server MCP: Risk & Policy

WHAT IT DOES

What update_device_property does on HC3 MCP Server

AI agents use update_device_property to create or update resources in HC3 MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your HC3 MCP Server environment.

WHY IT NEEDS A POLICY

Why update_device_property needs a policy

This tool modifies device properties in a Fibaro Home Center 3 smart home system, which is a Write operation—it changes state but is typically reversible. Severity is high because misuse could alter critical smart home device configurations (locks, thermostats, lighting, sensors), potentially affecting security, comfort, or safety, though the impact is narrower than Destructive actions.

From the tool's definition Tool name 'update_device_property' and description 'Update a device property value directly' indicate modification of device state in a smart home system. The verb 'update' combined with 'property value' shows reversible data modification.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_device_property Rate-limited

update_device_property 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": {
    "update_device_property": {
      "limits": [
        {
          "counter": "update_device_property_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 HC3 MCP Server, so you can run agents against it safely.

FAQ

Questions about update_device_property

What does the update_device_property tool do? +

Update a device property value directly. It is categorised as a Write tool in the HC3 MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_device_property? +

Register the HC3 MCP Server MCP server in PolicyLayer and add a rule for update_device_property: 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 HC3 MCP Server. Nothing to install.

What risk level is update_device_property? +

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

Can I rate-limit update_device_property? +

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

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

update_device_property is provided by the HC3 MCP Server MCP server (jangabrielsson/hc3_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.