generate_variation · Filopastry MCP: Risk & Policy

WHAT IT DOES

What generate_variation does on Filopastry

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

WHY IT NEEDS A POLICY

Why generate_variation needs a policy

The tool creates pattern variations within the Strudel.cc live coding environment. This is a Write operation as it generates/creates new content (music patterns). There is no evidence of destructive behavior, financial transactions, or code execution with system-level effects. The blast radius is low as it only affects music patterns within the application context.

From the tool's definition 'Create pattern variations' — generates new musical pattern content

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

generate_variation Rate-limited

generate_variation 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": {
    "generate_variation": {
      "limits": [
        {
          "counter": "generate_variation_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 Filopastry, so you can run agents against it safely.

FAQ

Questions about generate_variation

What does the generate_variation tool do? +

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

How do I enforce a policy on generate_variation? +

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

What risk level is generate_variation? +

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

Can I rate-limit generate_variation? +

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

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

generate_variation is provided by the Filopastry MCP server (youwenshao/filopastry). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.