AI agents call list_installed_fx to retrieve information from Orpheus without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
list_installed_fx retrieves and queries plugin information from REAPER's cache files to enable filtering recommendations. This is a non-destructive read operation with no side effects on the system or audio project. The tool gathers data to inform other operations but does not create, modify, delete, or execute anything itself.
From the tool's definition Tool description states 'Parse REAPER's plugin cache .ini files' - parsing is a read-only operation that retrieves and queries data from existing configuration files without modifying them.
Attacks that exploit this kind of access
Parse REAPER's plugin cache .ini files so recommendations only suggest owned plugins. It is categorised as a Read tool in the Orpheus MCP Server, which means it retrieves data without modifying state.
Register the Orpheus MCP server in PolicyLayer and add a rule for list_installed_fx: 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.
list_installed_fx is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the list_installed_fx 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.
Set action: deny in the PolicyLayer policy for list_installed_fx. 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.
list_installed_fx 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.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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