list_workspaces

THE RISK

Low Risk

Why list_workspaces needs a policy

This tool retrieves information about workspaces available to the user with no side effects, creation, deletion, or execution of operations. It is a standard discovery/enumeration function that fits the Read category. Severity is low because unauthorized workspace listing poses minimal direct risk—it primarily enables reconnaissance rather than data compromise or operational disruption.

From the tool's definition Tool name 'list_workspaces' and description 'List all Fabric workspaces accessible to the current user' indicate a read-only query operation that retrieves workspace metadata without modification.

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

POLICY

How to control list_workspaces

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_workspaces:

policy.json

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

list_workspaces 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

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All 45 Fabric Ontology MCP Server tools →

Read tools on other servers

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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_workspaces

What does the list_workspaces tool do? +

List all Fabric workspaces accessible to the current user. 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_workspaces? +

Register the Fabric Ontology MCP Server MCP server in PolicyLayer and add a rule for list_workspaces: 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_workspaces? +

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

Can I rate-limit list_workspaces? +

Yes. Add a rate_limit block to the list_workspaces 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_workspaces completely? +

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

list_workspaces 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 →