render_stems · Orpheus MCP: Risk & Policy

WHAT IT DOES

What render_stems does on Orpheus

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

WHY IT NEEDS A POLICY

Why render_stems needs a policy

Rendering stems creates new output files from existing audio tracks—a reversible write operation that modifies the project's output state. The tool doesn't execute arbitrary code or delete data (which would be Execute or Destructive), but it does write significant audio data to disk.

From the tool's definition Tool name 'render_stems' and description 'Render per-track stems by sequential solo' indicates the tool creates audio files (stems) from a REAPER project. Rendering produces new files that are written to disk.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

render_stems Rate-limited

render_stems 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": {
    "render_stems": {
      "limits": [
        {
          "counter": "render_stems_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 Orpheus, so you can run agents against it safely.

FAQ

Questions about render_stems

What does the render_stems tool do? +

Render per-track stems by sequential solo — feeds analyze_audio_character. It is categorised as a Write tool in the Orpheus MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on render_stems? +

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

What risk level is render_stems? +

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

Can I rate-limit render_stems? +

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

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

render_stems is provided by the Orpheus MCP server (mal0ware/orpheus). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.