create_watchlist · Wago Plc MCP: Risk & Policy

WHAT IT DOES

What create_watchlist does on Wago Plc

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

WHY IT NEEDS A POLICY

Why create_watchlist needs a policy

This tool creates persistent server-side state (a watchlist) for parameter monitoring. It is a Write operation because it creates/configures new resources reversibly. Severity is medium because while watchlist creation is reversible and doesn't directly control critical PLC operations or delete data, it modifies server state and could interfere with monitoring if misconfigured by an agent.

From the tool's definition create_watchlist: 'Create a server-side watchlist of parameters' — this creates new configuration on the PLC server side.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_watchlist Rate-limited

create_watchlist 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": {
    "create_watchlist": {
      "limits": [
        {
          "counter": "create_watchlist_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 Wago Plc, so you can run agents against it safely.

FAQ

Questions about create_watchlist

What does the create_watchlist tool do? +

Create a server-side watchlist of parameters for efficient repeated polling. It is categorised as a Write tool in the Wago Plc MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_watchlist? +

Register the Wago Plc MCP server in PolicyLayer and add a rule for create_watchlist: 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 Wago Plc. Nothing to install.

What risk level is create_watchlist? +

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

Can I rate-limit create_watchlist? +

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

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

create_watchlist is provided by the Wago Plc MCP server (wagoalex/wago-plc-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.