control_lights

THE RISK

Medium Risk

Why control_lights needs a policy

This tool modifies the state of the robot's lights (on/off). It is a reversible write operation with minimal blast radius — toggling lights has no impact on protocols, data, or physical lab operations.

From the tool's definition Turn robot lights on or off

Documented attack patterns abuse exactly the kind of access control_lights gives an agent:

POLICY

How to control control_lights

PolicyLayer is an MCP gateway — it sits between your AI agents and Opentrons MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for control_lights:

policy.json

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

control_lights 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.

Create a free account and register Opentrons MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Opentrons MCP Server tools

Execute control_run Control run execution (play, pause, stop, resume) Execute home_robot Home robot axes or specific pipette Execute poll_error_endpoint_and_fix Fetch specific JSON error report and automatically fix protocols Execute create_run Create a new protocol run on the robot Write upload_protocol Upload a protocol file to an Opentrons robot Read get_api_overview Get high-level overview of the Opentrons HTTP API structure and capabilities Read get_endpoint_details Get comprehensive details about a specific API endpoint Read get_protocols List all protocols stored on the robot

All 14 Opentrons MCP Server tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about control_lights

What does the control_lights tool do? +

Turn robot lights on or off. It is categorised as a Write tool in the Opentrons 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 control_lights? +

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

What risk level is control_lights? +

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

Can I rate-limit control_lights? +

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

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

control_lights is provided by the Opentrons MCP Server MCP server (yerbymatey/opentrons-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Opentrons MCP Server tool call.

Start from Opentrons MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →