prometheus_query · Overwatch MCP: Risk & Policy

WHAT IT DOES

What prometheus_query does on Overwatch MCP

AI agents invoke prometheus_query to trigger actions in Overwatch MCP. 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 prometheus_query needs a policy

The tool executes arbitrary PromQL queries. While standard PromQL is read-only (it retrieves metric values), the framing as 'execute' and the ability to run arbitrary queries warrants the Execute category. Misuse could expose sensitive metrics or be used to probe infrastructure, giving it medium severity.

From the tool's definition "Execute instant PromQL query" — the tool runs a PromQL query against Prometheus

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

prometheus_query Rate-limited

prometheus_query 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": {
    "prometheus_query": {
      "limits": [
        {
          "counter": "prometheus_query_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 Overwatch MCP, so you can run agents against it safely.

FAQ

Questions about prometheus_query

What does the prometheus_query tool do? +

Execute instant PromQL query for current metric values. It is categorised as a Execute tool in the Overwatch MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on prometheus_query? +

Register the Overwatch MCP server in PolicyLayer and add a rule for prometheus_query: 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 Overwatch MCP. Nothing to install.

What risk level is prometheus_query? +

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

Can I rate-limit prometheus_query? +

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

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

prometheus_query is provided by the Overwatch MCP server (malindarathnayake/overwatch-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.