files_create_folder · Pyfastmail MCP: Risk & Policy

WHAT IT DOES

What files_create_folder does on Pyfastmail

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

WHY IT NEEDS A POLICY

Why files_create_folder needs a policy

This tool creates a new folder in file storage, which is a reversible Write operation (the folder can be deleted). It does not execute code, delete data, move money, or read sensitive information directly. The medium severity reflects that an AI agent could clutter the file system or create folders that interfere with the user's organizational structure, but the impact is easily remedied by deleting the folders.

From the tool's definition Tool name: files_create_folder. Description: 'Create a folder on Fastmail Files (WebDAV).' The verb 'Create' and the action of creating a new folder both indicate data creation without deletion or irreversibility.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

files_create_folder Rate-limited

files_create_folder 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": {
    "files_create_folder": {
      "limits": [
        {
          "counter": "files_create_folder_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Pyfastmail, so you can run agents against it safely.

FAQ

Questions about files_create_folder

What does the files_create_folder tool do? +

Create a folder on Fastmail Files (WebDAV). It is categorised as a Write tool in the Pyfastmail MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on files_create_folder? +

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

What risk level is files_create_folder? +

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

Can I rate-limit files_create_folder? +

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

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

files_create_folder is provided by the Pyfastmail MCP server (pjosols/pyfastmail-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.