extract_attachments · Tbird MCP: Risk & Policy

WHAT IT DOES

What extract_attachments does on Tbird

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

WHY IT NEEDS A POLICY

Why extract_attachments needs a policy

This tool writes files to the local filesystem (saves attachments to a destination directory). It creates new files on disk, which is a reversible Write operation. It does not delete data, execute code, or involve financial transactions. Misuse could write unwanted or malicious files to arbitrary directories if dest_dir is attacker-controlled.

From the tool's definition Save a message's attachments to ``dest_dir``; returns the written file paths.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

extract_attachments Rate-limited

extract_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": {
    "extract_attachments": {
      "limits": [
        {
          "counter": "extract_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 Tbird, so you can run agents against it safely.

FAQ

Questions about extract_attachments

What does the extract_attachments tool do? +

Save a message's attachments to dest_dir; returns the written file paths. It is categorised as a Write tool in the Tbird MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on extract_attachments? +

Register the Tbird MCP server in PolicyLayer and add a rule for extract_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 Tbird. Nothing to install.

What risk level is extract_attachments? +

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

Can I rate-limit extract_attachments? +

Yes. Add a rate_limit block to the extract_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 extract_attachments completely? +

Set action: deny in the PolicyLayer policy for extract_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 extract_attachments? +

extract_attachments is provided by the Tbird MCP server (neil-zielsdorf/tbird-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.