Add URL pattern to global filter list (blacklist or whitelist depending on mode)
AI agents use add_url_filter to create or update resources in ASUS Merlin Router MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your ASUS Merlin Router MCP Server environment.
This tool modifies router configuration by adding URL filtering rules. While it doesn't delete data or execute arbitrary commands, it does create new security policy entries that affect network traffic routing.
From the tool's definition The tool 'add_url_filter' creates new entries in the router's filter list via 'Add URL pattern to global filter list'. This is a create/modify operation that adds data to a filtering rule set, making it a Write action.
Documented attack patterns abuse exactly the kind of access add_url_filter gives an agent:
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 add_url_filter:
{
"version": "1",
"default": "deny",
"tools": {
"add_url_filter": {
"limits": [
{
"counter": "add_url_filter_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}add_url_filter stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Add URL pattern to global filter list (blacklist or whitelist depending on mode). It is categorised as a Write tool in the ASUS Merlin Router MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the ASUS Merlin Router MCP Server MCP server in PolicyLayer and add a rule for add_url_filter: 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.
add_url_filter is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the add_url_filter 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.
Set action: deny in the PolicyLayer policy for add_url_filter. 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.
add_url_filter 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.
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.
Free to start. No card required.
47 ASUS Merlin Router MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.