create_folder · Joplin MCP: Risk & Policy

WHAT IT DOES

What create_folder does on Joplin

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

WHY IT NEEDS A POLICY

Why create_folder needs a policy

This tool creates a new folder/notebook, which is a reversible write operation. It does not execute code, delete data, move money, or have destructive effects. The severity is low because creating a folder in a note application has minimal blast radius—it creates an empty organizational structure with no side effects on existing data. The operation can be easily undone by deleting the folder.

From the tool's definition Tool name 'create_folder' and description 'Create a new folder/notebook in Joplin' explicitly describe creation of a new entity in the note-taking application.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_folder Rate-limited

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": {
    "create_folder": {
      "limits": [
        {
          "counter": "create_folder_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 Joplin, so you can run agents against it safely.

FAQ

Questions about create_folder

What does the create_folder tool do? +

Create a new folder/notebook in Joplin. It is categorised as a Write tool in the Joplin MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_folder? +

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

What risk level is create_folder? +

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

Can I rate-limit create_folder? +

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

Set action: deny in the PolicyLayer policy for 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 create_folder? +

create_folder is provided by the Joplin MCP server (joplin-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.