download_attachments · Email MCP: Risk & Policy

WHAT IT DOES

What download_attachments does on Email

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

WHY IT NEEDS A POLICY

Why download_attachments needs a policy

This tool reads attachments from an email and writes them to disk. The primary effect is creating new files on the filesystem, which is a Write operation. It is reversible (files can be deleted). Misuse could save malicious attachments to disk, hence medium severity.

From the tool's definition 'Save real (non-inline) attachments from an email to a descriptive subfolder under the user\' — the tool writes files to the local filesystem

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

download_attachments Rate-limited

download_attachments 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": {
    "download_attachments": {
      "limits": [
        {
          "counter": "download_attachments_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 Email, so you can run agents against it safely.

FAQ

Questions about download_attachments

What does the download_attachments tool do? +

Save real (non-inline) attachments from an email to a descriptive subfolder under the user\. It is categorised as a Write tool in the Email MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on download_attachments? +

Register the Email MCP server in PolicyLayer and add a rule for download_attachments: 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 Email. Nothing to install.

What risk level is download_attachments? +

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

Can I rate-limit download_attachments? +

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

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

download_attachments is provided by the Email MCP server (kerodkibatu/email-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.