download_attachment · Rocket Cli MCP: Risk & Policy

WHAT IT DOES

What download_attachment does on Rocket Cli

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

WHY IT NEEDS A POLICY

Why download_attachment needs a policy

This tool fetches remote data (Read aspect) but its primary effect is writing a file to local disk, which is a persistent side effect. It is reversible (the file can be deleted), so Write is the most appropriate category. Severity is medium because an agent could download malicious or sensitive content to the local system, but it does not delete or execute anything.

From the tool's definition 'Download a message attachment to local disk' — writes a file to the local filesystem

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

download_attachment Rate-limited

download_attachment 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_attachment": {
      "limits": [
        {
          "counter": "download_attachment_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 Rocket Cli, so you can run agents against it safely.

FAQ

Questions about download_attachment

What does the download_attachment tool do? +

Download a message attachment to local disk. The fileUrl comes from a. It is categorised as a Write tool in the Rocket Cli 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_attachment? +

Register the Rocket Cli MCP server in PolicyLayer and add a rule for download_attachment: 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 Rocket Cli. Nothing to install.

What risk level is download_attachment? +

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

Can I rate-limit download_attachment? +

Yes. Add a rate_limit block to the download_attachment 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_attachment completely? +

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

download_attachment is provided by the Rocket Cli MCP server (jeanfbrito/rocket-cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.