Set time signature.
AI agents use transport_set_time_signature to create or update resources in ReaperMCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your ReaperMCP environment.
This tool creates or modifies project configuration data (time signature) reversibly. It does not execute arbitrary code, delete data irreversibly, or trigger financial transactions. The impact is localized to the timing grid of a music project, which can be easily undone or changed, making it Write rather than Execute.
From the tool's definition Tool name 'transport_set_time_signature' and description 'Set time signature' indicate the tool modifies project metadata—specifically the time signature setting in a REAPER session.
Documented attack patterns abuse exactly the kind of access transport_set_time_signature gives an agent:
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 transport_set_time_signature:
{
"version": "1",
"default": "deny",
"tools": {
"transport_set_time_signature": {
"limits": [
{
"counter": "transport_set_time_signature_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}transport_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 time signature. It is categorised as a Write tool in the ReaperMCP 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 transport_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 ReaperMCP. Nothing to install.
transport_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 transport_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 transport_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.
transport_set_time_signature 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.
Start from ReaperMCP, 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.
138 ReaperMCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.