list_url_filters

THE RISK

Low Risk

Why list_url_filters needs a policy

This tool retrieves and displays URL filter rules without modifying, executing, or deleting anything. It is a read-only query of router configuration data. The severity is low because unauthorized access to filter rule configuration is informational exposure rather than operational risk.

From the tool's definition Tool name 'list_url_filters' and description 'List all configured URL filter rules with status and mode' indicate data retrieval with no side effects. The verb 'list' is a classic read operation that queries existing configuration.

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

POLICY

How to control list_url_filters

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

policy.json

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

list_url_filters 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 ASUS Merlin Router 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.

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EXPLORE

Related tools and policies

More ASUS Merlin Router MCP Server tools

Destructive remove_dhcp_reservation Remove DHCP reservation by MAC or IP address Destructive remove_keyword_filter Remove keyword from filter list Destructive remove_mac_filter Remove device from MAC filter Destructive remove_network_service_filter_rule Remove network service filter rule by matching all criteria exactly Destructive remove_url_filter Remove URL pattern from global filter list Destructive remove_vpn_routing_policy Remove device from VPN Director routing (Asuswrt-Merlin firmware only). Device will return Execute execute_command Execute a custom command on the router via SSH. WARNING: NEVER use this for file operation Execute restart_service Restart a specific router service (e.g., wireless, vpnclient1, httpd)

All 47 ASUS Merlin Router 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_url_filters

What does the list_url_filters tool do? +

List all configured URL filter rules with status and mode. It is categorised as a Read tool in the ASUS Merlin Router MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_url_filters? +

Register the ASUS Merlin Router MCP Server MCP server in PolicyLayer and add a rule for list_url_filters: 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 ASUS Merlin Router MCP Server. Nothing to install.

What risk level is list_url_filters? +

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

Can I rate-limit list_url_filters? +

Yes. Add a rate_limit block to the list_url_filters 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_url_filters completely? +

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

list_url_filters is provided by the ASUS Merlin Router MCP Server MCP server (kcsoukup/asus-merlin-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every ASUS Merlin Router MCP Server tool call.

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

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