vna_save_screenshot · Copper Mountain Vna MCP: Risk & Policy

WHAT IT DOES

What vna_save_screenshot does on Copper Mountain Vna

AI agents use vna_save_screenshot 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_screenshot needs a policy

Saving a screenshot creates a new file artifact but does not modify the analyzer's configuration, measurements, or calibration state. It is a read-like operation with a side effect of file creation (Write category). The severity is low because screenshot files are typically non-sensitive diagnostic data and cannot cause harm to the instrument or its operations.

From the tool's definition Tool name 'vna_save_screenshot' and description 'Save VNA display screenshot' indicate this tool writes/exports data (a screenshot file) from the Vector Network Analyzer.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

vna_save_screenshot Rate-limited

vna_save_screenshot 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_screenshot": {
      "limits": [
        {
          "counter": "vna_save_screenshot_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_screenshot

What does the vna_save_screenshot tool do? +

Save VNA display screenshot. 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_screenshot? +

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

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

Can I rate-limit vna_save_screenshot? +

Yes. Add a rate_limit block to the vna_save_screenshot 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_screenshot completely? +

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

vna_save_screenshot 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.