list_create · Mastodon MCP: Risk & Policy

WHAT IT DOES

What list_create does on Mastodon

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

WHY IT NEEDS A POLICY

Why list_create needs a policy

Creating a list is a reversible write operation with minimal blast radius; it does not delete data, execute code, or involve financial transactions.

From the tool's definition 'Create a new list' — creates a new resource (a list) on the Mastodon instance

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

list_create Rate-limited

list_create 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": {
    "list_create": {
      "limits": [
        {
          "counter": "list_create_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 Mastodon, so you can run agents against it safely.

FAQ

Questions about list_create

What does the list_create tool do? +

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

How do I enforce a policy on list_create? +

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

What risk level is list_create? +

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

Can I rate-limit list_create? +

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

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

list_create is provided by the Mastodon MCP server (vitexsoftware/mastodon-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.