update_unit · Mealie MCP Server MCP: Risk & Policy

WHAT IT DOES

What update_unit does on Mealie MCP Server

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

WHY IT NEEDS A POLICY

Why update_unit needs a policy

This tool modifies existing data (measurement units) reversibly—updates can be undone by subsequent updates or restoration. It does not delete data irreversibly, execute arbitrary code, or move money. The impact is scoped to unit definitions, affecting potentially many recipes that reference those units, warranting medium severity for a misconfigured or unintended update.

From the tool's definition Tool description states 'Update an existing measurement unit', which is a modification operation. The name 'update_unit' and description explicitly indicate changing existing data (a measurement unit) in the Mealie system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_unit Rate-limited

update_unit 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": {
    "update_unit": {
      "limits": [
        {
          "counter": "update_unit_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 Mealie MCP Server, so you can run agents against it safely.

FAQ

Questions about update_unit

What does the update_unit tool do? +

Update an existing measurement unit in Mealie. It is categorised as a Write tool in the Mealie 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 update_unit? +

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

What risk level is update_unit? +

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

Can I rate-limit update_unit? +

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

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

update_unit is provided by the Mealie MCP Server MCP server (nikopol666/mealie-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.