vm_prometheus_write · Victoriametrics MCP: Risk & Policy

WHAT IT DOES

What vm_prometheus_write does on Victoriametrics

AI agents use vm_prometheus_write to create or update resources in Victoriametrics — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Victoriametrics environment.

WHY IT NEEDS A POLICY

Why vm_prometheus_write needs a policy

This tool writes data into a metrics database (VictoriaMetrics). While not destructive (data can be overwritten or corrected), importing arbitrary or malicious time-series data could corrupt monitoring data, trigger false alerts, or degrade system visibility. The severity is high because misuse affects observability integrity across potentially many monitored systems.

From the tool's definition Tool name 'vm_prometheus_write' and description 'Import Prometheus exposition format data into VictoriaMetrics' indicate the tool creates or modifies time-series data by importing metrics.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

vm_prometheus_write Rate-limited

vm_prometheus_write 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "vm_prometheus_write": {
      "limits": [
        {
          "counter": "vm_prometheus_write_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about vm_prometheus_write

What does the vm_prometheus_write tool do? +

mport Prometheus exposition format data into VictoriaMetrics. It is categorised as a Write tool in the Victoriametrics MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on vm_prometheus_write? +

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

What risk level is vm_prometheus_write? +

vm_prometheus_write is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit vm_prometheus_write? +

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

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

vm_prometheus_write is provided by the Victoriametrics MCP server (@yincongcyincong/victoriametrics-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.