fx_navigate_preset

THE RISK

High Risk

Why fx_navigate_preset needs a policy

This tool triggers navigation through effect presets, which modifies the active state of REAPER's audio processing chain and produces audible/structural effects on the project. While not destructive or persistent data modification, it qualifies as Execute because it actively changes the state of an external system (REAPER's DSP/effects chain) based on the instruction.

From the tool's definition Tool name 'fx_navigate_preset' with action verb 'navigate' to step through presets. In the context of REAPER music production, this performs an external operation that changes active audio processing state (preset switching).

Documented attack patterns abuse exactly the kind of access fx_navigate_preset gives an agent:

POLICY

How to control fx_navigate_preset

PolicyLayer is an MCP gateway — it sits between your AI agents and ReaperMCP, and nothing reaches the server without passing your rules. This is the rule we recommend for fx_navigate_preset:

policy.json

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

fx_navigate_preset 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.

Create a free account and register ReaperMCP — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

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All 138 ReaperMCP tools →

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Go deeper

High-risk tools in ReaperMCP → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about fx_navigate_preset

What does the fx_navigate_preset tool do? +

Step to next/previous preset. It is categorised as a Execute tool in the ReaperMCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on fx_navigate_preset? +

Register the Reaper MCP server in PolicyLayer and add a rule for fx_navigate_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 ReaperMCP. Nothing to install.

What risk level is fx_navigate_preset? +

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

Can I rate-limit fx_navigate_preset? +

Yes. Add a rate_limit block to the fx_navigate_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 fx_navigate_preset completely? +

Set action: deny in the PolicyLayer policy for fx_navigate_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 fx_navigate_preset? +

fx_navigate_preset is provided by the Reaper MCP server (xdarkzx/reaper-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every ReaperMCP tool call.

Start from ReaperMCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →