write_coil

A write tool on the Pypi:labmcp Alicat MCP server.

SERVERPypi:labmcp Alicat SOURCEpypi:labmcp-alicat

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/lab-instrument-mcps/write-coil.md

WHAT IT DOES

What write_coil does on Pypi:labmcp Alicat

AI agents use write_coil to create or update resources in Pypi:labmcp Alicat, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Pypi:labmcp Alicat environment.

RISK

Why write_coil is rated Medium

Modbus coils control physical industrial equipment and processes. Writing to coils can change the state of connected devices (pumps, motors, valves, etc.). While not destructive in the data-deletion sense, misuse could cause unintended physical actions. The empty description lowers confidence slightly, but the name and context are sufficiently clear.

From the tool's definition Tool name is 'write_coil' and is part of the Modbus protocol toolset. Modbus coils are binary output registers that control physical devices. The 'write_' prefix indicates a modification operation.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs write_coil safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Pypi:labmcp Alicat, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For write_coil, this is the rule to start with:

write_coil Rate-limited

write_coil 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": {
    "write_coil": {
      "limits": [
        {
          "counter": "write_coil_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Pypi:labmcp Alicat, apply this rule, and every write_coil call is checked against it from then on.

FAQ

Questions about write_coil

What does the write_coil tool do? +

write_coil is a write tool on the Pypi:labmcp Alicat MCP server. It is categorised as a Write tool in the Pypi:labmcp Alicat MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on write_coil? +

Register the Pypi:labmcp Alicat MCP server in PolicyLayer and add a rule for write_coil: 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 Pypi:labmcp Alicat. Nothing to install.

What risk level is write_coil? +

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

Can I rate-limit write_coil? +

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

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

write_coil is provided by the Pypi:labmcp Alicat MCP server (pypi:labmcp-alicat). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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