prom_query · RedisNexus MCP: Risk & Policy

WHAT IT DOES

What prom_query does on RedisNexus

AI agents invoke prom_query to trigger actions in RedisNexus. 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 prom_query needs a policy

The tool explicitly executes PromQL queries against Prometheus. While typical PromQL is read-only for metrics, 'execute' of arbitrary queries against a production monitoring system carries medium-to-high risk — a misconfigured or malicious query could cause high load on Prometheus or expose sensitive operational metrics. The word 'Execute' in the description confirms the Execute category, which ranks above Read.

From the tool's definition "Execute instant or range PromQL queries against Prometheus"

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

prom_query Rate-limited

prom_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": {
    "prom_query": {
      "limits": [
        {
          "counter": "prom_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 RedisNexus, so you can run agents against it safely.

FAQ

Questions about prom_query

What does the prom_query tool do? +

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

How do I enforce a policy on prom_query? +

Register the RedisNexus MCP server in PolicyLayer and add a rule for prom_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 RedisNexus. Nothing to install.

What risk level is prom_query? +

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

Can I rate-limit prom_query? +

Yes. Add a rate_limit block to the prom_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 prom_query completely? +

Set action: deny in the PolicyLayer policy for prom_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 prom_query? +

prom_query is provided by the RedisNexus MCP server (rajkumar-madhu/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.