set_spot_size · mcpXL30 MCP: Risk & Policy

WHAT IT DOES

What set_spot_size does on mcpXL30

AI agents use set_spot_size to create or update resources in mcpXL30 — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your mcpXL30 environment.

WHY IT NEEDS A POLICY

Why set_spot_size needs a policy

Based on the tool name, 'set_spot_size' likely adjusts the electron beam spot size parameter on the microscope, which is a write/configuration operation modifying instrument state. Sibling tools like 'get_beam_shift', 'get_brightness', and 'set_*' patterns suggest paired get/set operations for beam parameters. Without a description, confidence is reduced, but the 'set_' prefix strongly implies a write action.

From the tool's definition Tool name 'set_spot_size' on a server controlling a Philips XL30 ESEM microscope; description is empty and uninformative.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_spot_size Rate-limited

set_spot_size 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": {
    "set_spot_size": {
      "limits": [
        {
          "counter": "set_spot_size_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 mcpXL30, so you can run agents against it safely.

FAQ

Questions about set_spot_size

What does the set_spot_size tool do? +

set_spot_size. It is categorised as a Write tool in the mcpXL30 MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_spot_size? +

Register the mcpXL30 MCP server in PolicyLayer and add a rule for set_spot_size: 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 mcpXL30. Nothing to install.

What risk level is set_spot_size? +

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

Can I rate-limit set_spot_size? +

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

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

set_spot_size is provided by the mcpXL30 MCP server (tspspi/mcpxl30). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.