AI agents call monitoring_get_metrics to retrieve information from OPNSense MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves system performance and health metrics from the OPNSense firewall for observability purposes. It performs a query operation that returns data without creating, modifying, deleting, or executing any actions on the system. The 'Get' operation and 'metrics' retrieval are characteristic of Read-category tools.
From the tool's definition Tool name 'monitoring_get_metrics' with description 'Get current system metrics' indicates retrieval of monitoring data with no modification or side effects.
Documented attack patterns abuse exactly the kind of access monitoring_get_metrics gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and OPNSense MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for monitoring_get_metrics:
{
"version": "1",
"default": "deny",
"tools": {
"monitoring_get_metrics": {}
}
}monitoring_get_metrics is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get current system metrics. It is categorised as a Read tool in the OPNSense MCP Server MCP Server, which means it retrieves data without modifying state.
Register the OPNSense MCP Server MCP server in PolicyLayer and add a rule for monitoring_get_metrics: 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 OPNSense MCP Server. Nothing to install.
monitoring_get_metrics is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the monitoring_get_metrics 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 monitoring_get_metrics. 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.
monitoring_get_metrics is provided by the OPNSense MCP Server MCP server (vespo92/opnsensemcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 196 OPNSense MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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196 OPNSense MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.