vna_set_marker · Copper Mountain Vna MCP: Risk & Policy

WHAT IT DOES

What vna_set_marker does on Copper Mountain Vna

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

WHY IT NEEDS A POLICY

Why vna_set_marker needs a policy

Setting a marker position modifies the instrument's display/measurement state by placing a marker at a specified frequency. This is a reversible configuration change with no destructive or financial implications. Blast radius is low as it only affects marker display on the VNA.

From the tool's definition Position marker at frequency

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

vna_set_marker Rate-limited

vna_set_marker 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": {
    "vna_set_marker": {
      "limits": [
        {
          "counter": "vna_set_marker_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 Copper Mountain Vna, so you can run agents against it safely.

FAQ

Questions about vna_set_marker

What does the vna_set_marker tool do? +

Position marker at frequency. It is categorised as a Write tool in the Copper Mountain Vna MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on vna_set_marker? +

Register the Copper Mountain Vna MCP server in PolicyLayer and add a rule for vna_set_marker: 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 Copper Mountain Vna. Nothing to install.

What risk level is vna_set_marker? +

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

Can I rate-limit vna_set_marker? +

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

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

vna_set_marker is provided by the Copper Mountain Vna MCP server (rfingadam/copper-mountain-vna-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.