set_parameters · Wago Plc MCP: Risk & Policy

WHAT IT DOES

What set_parameters does on Wago Plc

AI agents use set_parameters 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 set_parameters needs a policy

This tool creates or modifies data reversibly via a PATCH call to set PLC parameters. While the operation itself is reversible (parameters can be changed back), the impact on physical systems controlled by PLCs is potentially severe. However, it does not irreversibly delete data (Destructive), execute arbitrary code (Execute), or move money (Financial), so Write is the correct category.

From the tool's definition The description explicitly states 'Write multiple parameters' and uses a PATCH HTTP method, which is a write operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_parameters Rate-limited

set_parameters 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_parameters": {
      "limits": [
        {
          "counter": "set_parameters_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 set_parameters

What does the set_parameters tool do? +

Write multiple parameters in one PATCH call. Pre-validates writeability from cache. 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 set_parameters? +

Register the Wago Plc MCP server in PolicyLayer and add a rule for set_parameters: 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 set_parameters? +

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

Can I rate-limit set_parameters? +

Yes. Add a rate_limit block to the set_parameters 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_parameters completely? +

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

set_parameters 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.