fl_call · Flemcee MCP: Risk & Policy

WHAT IT DOES

What fl_call does on Flemcee

AI agents invoke fl_call to trigger actions in Flemcee. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why fl_call needs a policy

This tool executes functions in a remote FL Studio process based on user-supplied dotted paths. While the example 'transport.start' appears benign, the general capability to 'call a dotted-path function' gives unrestricted access to the FL Studio API surface. An adversarial or misdirected agent could call destructive functions (e.g., deleting projects, overwriting files, or triggering unwanted audio output).

From the tool's definition Tool description states 'Call a dotted-path function inside FL Studio' — this directly executes arbitrary functions within the FL Studio environment. The sibling tools include 'fl_eval' and 'fl_exec', confirming this server is designed for code execution.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

fl_call Rate-limited

fl_call stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "fl_call": {
      "limits": [
        {
          "counter": "fl_call_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about fl_call

What does the fl_call tool do? +

Call a dotted-path function inside FL Studio (e.g. 'transport.start'). It is categorised as a Execute tool in the Flemcee MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on fl_call? +

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

What risk level is fl_call? +

fl_call is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit fl_call? +

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

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

fl_call is provided by the Flemcee MCP server (tylerjharden/flemcee). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.