query_prometheus · Grafana MCP Server MCP: Risk & Policy

WHAT IT DOES

What query_prometheus does on Grafana MCP Server

AI agents invoke query_prometheus to trigger actions in Grafana MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why query_prometheus needs a policy

This tool runs arbitrary PromQL queries against a Prometheus datasource. While read-only in nature for typical metric queries, PromQL execution is an active operation against an external system whose effects depend on the query arguments. It could be used to execute expensive queries that overload the Prometheus server (denial of service), expose sensitive metrics, or be chained with other tools for reconnaissance.

From the tool's definition Execute a PromQL query against a Prometheus datasource

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

query_prometheus Rate-limited

query_prometheus stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "query_prometheus": {
      "limits": [
        {
          "counter": "query_prometheus_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Grafana MCP Server, so you can run agents against it safely.

FAQ

Questions about query_prometheus

What does the query_prometheus tool do? +

Execute a PromQL query against a Prometheus datasource. It is categorised as a Execute tool in the Grafana MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on query_prometheus? +

Register the Grafana MCP Server MCP server in PolicyLayer and add a rule for query_prometheus: 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 Grafana MCP Server. Nothing to install.

What risk level is query_prometheus? +

query_prometheus is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit query_prometheus? +

Yes. Add a rate_limit block to the query_prometheus 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 query_prometheus completely? +

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

query_prometheus is provided by the Grafana MCP Server MCP server (quanticsoul4772/grafana-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.