list_custom_apps

THE RISK

Low Risk

Why list_custom_apps needs a policy

This tool retrieves and displays status information about existing custom applications without creating, modifying, deleting, or executing any operations. It is a pure read operation with no side effects, fitting the Read category. Severity is low as disclosure of this information alone does not enable harmful actions without additional write or destructive tools.

From the tool's definition Tool name 'list_custom_apps' and description 'List all Custom Apps with status information' indicate a query/retrieval operation with no modification or deletion capabilities.

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

POLICY

How to control list_custom_apps

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

policy.json

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

list_custom_apps 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 TrueNAS Scale 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 →

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EXPLORE

Related tools and policies

More TrueNAS Scale MCP Server tools

Destructive delete_custom_app Delete a Custom App and optionally its data volumes Destructive cleanup_stale_containers Clean up stale containers and fix conflicts Execute bulk_app_operation Start/stop multiple apps at once Execute deploy_custom_app Deploy a new Custom App from Docker Compose configuration Execute start_custom_app Start a stopped Custom App Execute stop_custom_app Stop a running Custom App Write update_custom_app Update an existing Custom App with new Docker Compose configuration Read diagnose_docker_issues Diagnose Docker engine issues and network conflicts

All 13 TrueNAS Scale 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_custom_apps

What does the list_custom_apps tool do? +

List all Custom Apps with status information. It is categorised as a Read tool in the TrueNAS Scale MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_custom_apps? +

Register the TrueNAS Scale MCP Server MCP server in PolicyLayer and add a rule for list_custom_apps: 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 TrueNAS Scale MCP Server. Nothing to install.

What risk level is list_custom_apps? +

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

Can I rate-limit list_custom_apps? +

Yes. Add a rate_limit block to the list_custom_apps 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_custom_apps completely? +

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

list_custom_apps is provided by the TrueNAS Scale MCP Server MCP server (svnstfns/truenas-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 TrueNAS Scale MCP Server tool call.

Start from TrueNAS Scale 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 →