update_mailbox_note · TrekMail MCP Server MCP: Risk & Policy

WHAT IT DOES

What update_mailbox_note does on TrekMail MCP Server

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

WHY IT NEEDS A POLICY

Why update_mailbox_note needs a policy

This tool modifies metadata (a note/description field) on a mailbox, which is a Write operation. The change is reversible—notes can be updated or cleared without data loss or irreversible consequences. The blast radius is minimal since it only affects a text field (max 120 characters) used for administrative documentation or labeling, not core mailbox functionality or data.

From the tool's definition Tool description states 'Update the note/description on a mailbox' and 'Pass null to clear', indicating reversible modification of mailbox metadata.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_mailbox_note Rate-limited

update_mailbox_note 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_mailbox_note": {
      "limits": [
        {
          "counter": "update_mailbox_note_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 TrekMail MCP Server, so you can run agents against it safely.

FAQ

Questions about update_mailbox_note

What does the update_mailbox_note tool do? +

Update the note/description on a mailbox (max 120 characters). Pass null to clear. It is categorised as a Write tool in the TrekMail 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_mailbox_note? +

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

What risk level is update_mailbox_note? +

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

Can I rate-limit update_mailbox_note? +

Yes. Add a rate_limit block to the update_mailbox_note 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_mailbox_note completely? +

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

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