save_theme_preset · Pen MCP: Risk & Policy

WHAT IT DOES

What save_theme_preset does on Pen

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

WHY IT NEEDS A POLICY

Why save_theme_preset needs a policy

This tool creates or modifies a .optheme preset file by persisting theme configuration data. It is reversible (the preset can be deleted or overwritten), so it falls under Write rather than Destructive.

From the tool's definition Tool saves themes and variables to a reusable .optheme preset file. The description explicitly uses 'save' which indicates creation or modification of a file artifact.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

save_theme_preset Rate-limited

save_theme_preset 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": {
    "save_theme_preset": {
      "limits": [
        {
          "counter": "save_theme_preset_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

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

FAQ

Questions about save_theme_preset

What does the save_theme_preset tool do? +

Save the themes and variables from an .op document as a reusable .optheme preset file. It is categorised as a Write tool in the Pen MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on save_theme_preset? +

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

What risk level is save_theme_preset? +

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

Can I rate-limit save_theme_preset? +

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

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

save_theme_preset is provided by the Pen MCP server (@zseven-w/pen-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.