mark_message · Mcp Imap MCP: Risk & Policy

WHAT IT DOES

What mark_message does on Mcp Imap

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

WHY IT NEEDS A POLICY

Why mark_message needs a policy

This tool modifies message state (flags/read status) but does not delete, create new messages, execute code, or move money. The changes are fully reversible—flags can be toggled on and off. It is categorized as Write rather than Read because it has side effects that change data state.

From the tool's definition Tool description explicitly states it can 'Set or remove flags on a message' including marking as read/unread and flag/unflag operations. These are reversible modifications to message metadata.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mark_message Rate-limited

mark_message 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": {
    "mark_message": {
      "limits": [
        {
          "counter": "mark_message_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 Mcp Imap, so you can run agents against it safely.

FAQ

Questions about mark_message

What does the mark_message tool do? +

Set or remove flags on a message (e.g., mark as read/unread, flag/unflag). It is categorised as a Write tool in the Mcp Imap MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on mark_message? +

Register the Mcp Imap MCP server in PolicyLayer and add a rule for mark_message: 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 Mcp Imap. Nothing to install.

What risk level is mark_message? +

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

Can I rate-limit mark_message? +

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

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

mark_message is provided by the Mcp Imap MCP server (ngcdan/mcp-imap-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.