Set the velocity of a MIDI note.
AI agents use set_midi_note_velocity 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 modifies MIDI note attributes (velocity) within a music production project. While the change is reversible and does not delete data, it constitutes a write operation that alters the state of the musical composition. Severity is medium because misuse could significantly alter a music project's sound character, but the effect is confined to a single MIDI parameter and can be undone.
From the tool's definition Tool name 'set_midi_note_velocity' and description 'Set the velocity of a MIDI note' indicate modification of MIDI note properties. This changes existing MIDI data by adjusting note velocity, which is a reversible parameter modification.
Documented attack patterns abuse exactly the kind of access set_midi_note_velocity 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_midi_note_velocity:
{
"version": "1",
"default": "deny",
"tools": {
"set_midi_note_velocity": {
"limits": [
{
"counter": "set_midi_note_velocity_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}set_midi_note_velocity 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.
Free to start. No card required.
Set the velocity of a MIDI note. 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_midi_note_velocity: 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_midi_note_velocity 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_midi_note_velocity 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_midi_note_velocity. 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_midi_note_velocity 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.