set_brightness · Ulanzi MCP: Risk & Policy

WHAT IT DOES

What set_brightness does on Ulanzi

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

WHY IT NEEDS A POLICY

Why set_brightness needs a policy

This tool modifies a device setting (brightness) but the change is completely reversible—brightness can be adjusted up or down at any time. It does not execute code, delete data, or move money. While it affects physical output (LED display), the operation has minimal blast radius and causes no permanent harm. Classified as Write with low severity due to the trivial nature of the modification.

From the tool's definition Tool name 'set_brightness' and description 'Set the matrix brightness' indicate a modification operation that changes device state (brightness level) reversibly.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_brightness Rate-limited

set_brightness 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_brightness": {
      "limits": [
        {
          "counter": "set_brightness_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 Ulanzi, so you can run agents against it safely.

FAQ

Questions about set_brightness

What does the set_brightness tool do? +

Set the matrix brightness. It is categorised as a Write tool in the Ulanzi 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_brightness? +

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

What risk level is set_brightness? +

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

Can I rate-limit set_brightness? +

Yes. Add a rate_limit block to the set_brightness 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_brightness completely? +

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

set_brightness is provided by the Ulanzi MCP server (jelloeater/ulanzi-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.