list_worlds

THE RISK

Low Risk

Why list_worlds needs a policy

This tool queries and retrieves information about previously generated worlds without creating, modifying, deleting, or executing any operations. It is a straightforward read operation that poses minimal security risk.

From the tool's definition Tool name is 'list_worlds' and description states 'List previously generated worlds.' The verb 'list' indicates a retrieval operation with no modification or side effects.

Documented attack patterns abuse exactly the kind of access list_worlds gives an agent:

POLICY

How to control list_worlds

PolicyLayer is an MCP gateway — it sits between your AI agents and Worldlabs, and nothing reaches the server without passing your rules. This is the rule we recommend for list_worlds:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "list_worlds": {}
  }
}

list_worlds is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Worldlabs — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Worldlabs tools

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about list_worlds

What does the list_worlds tool do? +

List previously generated worlds. It is categorised as a Read tool in the Worldlabs MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_worlds? +

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

What risk level is list_worlds? +

list_worlds is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit list_worlds? +

Yes. Add a rate_limit block to the list_worlds 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_worlds completely? +

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

list_worlds is provided by the Worldlabs MCP server (sandraschi/worldlabs-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Worldlabs tool call.

Start from Worldlabs, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →