vna_save_touchstone · Copper Mountain Vna MCP: Risk & Policy

WHAT IT DOES

What vna_save_touchstone does on Copper Mountain Vna

AI agents use vna_save_touchstone 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_save_touchstone needs a policy

This tool creates or modifies files on the measurement system by exporting S-parameter data. It is reversible (files can be re-exported or deleted), so it falls under Write rather than Destructive. The blast radius is low because file export operations typically have minimal side effects on the VNA hardware state or connected systems. No data is deleted, financial impact occurs, or arbitrary code is executed.

From the tool's definition Tool exports/saves data to file format (.s1p/.s2p/.s4p Touchstone files). The verb 'save' and context of 'Export S-parameter data to Touchstone file' indicate creation of new files or overwriting existing measurement exports.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

vna_save_touchstone Rate-limited

vna_save_touchstone 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_save_touchstone": {
      "limits": [
        {
          "counter": "vna_save_touchstone_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_save_touchstone

What does the vna_save_touchstone tool do? +

Export S-parameter data to Touchstone file (.s1p/.s2p/.s4p). 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_save_touchstone? +

Register the Copper Mountain Vna MCP server in PolicyLayer and add a rule for vna_save_touchstone: 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_save_touchstone? +

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

Can I rate-limit vna_save_touchstone? +

Yes. Add a rate_limit block to the vna_save_touchstone 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_save_touchstone completely? +

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

vna_save_touchstone 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.