set_light · Hue MCP: Risk & Policy

WHAT IT DOES

What set_light does on HueMCP

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

WHY IT NEEDS A POLICY

Why set_light needs a policy

The tool modifies lighting device state (on/off, brightness, color, etc.), which is reversible and non-destructive. This constitutes Write rather than Execute because it targets a specific resource state change rather than running arbitrary code. Severity is medium: misuse could disrupt occupant comfort or smart home routines, but has no financial, destructive, or safety-critical consequences in typical scenarios.

From the tool's definition Tool name 'set_light' combined with sibling tools 'set_group' and context of 'control of Philips Hue lighting devices' indicates modification of light state. Description is empty, requiring inference from name and server context.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_light Rate-limited

set_light 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_light": {
      "limits": [
        {
          "counter": "set_light_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 HueMCP, so you can run agents against it safely.

FAQ

Questions about set_light

What does the set_light tool do? +

set_light. It is categorised as a Write tool in the HueMCP 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_light? +

Register the Hue MCP server in PolicyLayer and add a rule for set_light: 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 HueMCP. Nothing to install.

What risk level is set_light? +

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

Can I rate-limit set_light? +

Yes. Add a rate_limit block to the set_light 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_light completely? +

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

set_light is provided by the Hue MCP server (mbruton/huemcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.