Set the project time signature.
AI agents use set_time_signature to create or update resources in Reaper — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Reaper environment.
This tool creates or modifies project settings reversibly. Changing the time signature affects how the DAW interprets musical timing and playback, but the change can be undone. It does not execute arbitrary code, delete data, or commit financial transactions. It fits the Write category as a project configuration modification.
From the tool's definition 'Set the project time signature' modifies project metadata (time signature), which is a reversible configuration change to the REAPER project.
Documented attack patterns abuse exactly the kind of access set_time_signature gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Reaper, and nothing reaches the server without passing your rules. This is the rule we recommend for set_time_signature:
{
"version": "1",
"default": "deny",
"tools": {
"set_time_signature": {
"limits": [
{
"counter": "set_time_signature_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}set_time_signature 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.
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Set the project time signature. It is categorised as a Write tool in the Reaper MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Reaper MCP server in PolicyLayer and add a rule for set_time_signature: 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 Reaper. Nothing to install.
set_time_signature is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the set_time_signature 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 set_time_signature. 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.
set_time_signature is provided by the Reaper MCP server (twelvetake-studios/reaper-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Reaper, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
158 Reaper tools catalogued and risk-classified — across an index of 43,000+ MCP servers.