list_entity_types

THE RISK

Low Risk

Why list_entity_types needs a policy

This tool performs a straightforward data retrieval operation (list/query) with no side effects. It reads ontology schema information and returns results to the user. There is no data modification, execution of code, deletion, or financial impact. The low severity reflects minimal risk even if an AI agent calls it unexpectedly, as it only exposes read-only metadata about entity type definitions.

From the tool's definition Tool name 'list_entity_types' and description 'List all entity types in an ontology' indicate a query operation that retrieves and displays existing ontology metadata without modification.

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

POLICY

How to control list_entity_types

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

policy.json

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

list_entity_types 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 Fabric Ontology MCP Server — 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 Fabric Ontology MCP Server tools

Destructive delete_ontology Delete an ontology. Destructive remove_contextualization Remove a contextualization from a relationship type. Destructive remove_data_binding Remove a data binding from an entity type. Destructive remove_document Remove a document from an entity type by its URL. Destructive remove_entity_type Remove an entity type from an ontology. Destructive remove_property Remove a property from an entity type. Destructive remove_relationship_type Remove a relationship type from an ontology. Write add_contextualization add_contextualization

All 45 Fabric Ontology MCP Server tools →

Read tools on other servers

M-Team MCP Server get_torrent_detail YouTube MCP Server search_channel Android Forensics ADB MCP Server parse_browser_history 0xarchive web3_challenge

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_entity_types

What does the list_entity_types tool do? +

List all entity types in an ontology. It is categorised as a Read tool in the Fabric Ontology MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_entity_types? +

Register the Fabric Ontology MCP Server MCP server in PolicyLayer and add a rule for list_entity_types: 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 Fabric Ontology MCP Server. Nothing to install.

What risk level is list_entity_types? +

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

Can I rate-limit list_entity_types? +

Yes. Add a rate_limit block to the list_entity_types 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_entity_types completely? +

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

list_entity_types is provided by the Fabric Ontology MCP Server MCP server (tmdaidevs/ontology-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Fabric Ontology MCP Server tool call.

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

CHECK YOUR STACK →