Undo the last action. Use for 'undo', 'undo that', 'go back', 'revert'.
AI agents use dsl_undo to create or update resources in REAPER MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your REAPER MCP Server environment.
Undo reverts data modifications made to a REAPER project, which constitutes a Write operation. It's not Destructive because undo itself is a standard, reversible operation with an inverse (redo). However, it poses medium severity risk because an AI agent calling undo repeatedly or at wrong times could discard user work or interrupt critical editing sessions.
From the tool's definition Tool name 'dsl_undo' and description 'Undo the last action' indicate reversal of prior modifications to DAW state. While undo is reversible in theory, it modifies the current working state and can lose redo history.
Documented attack patterns abuse exactly the kind of access dsl_undo gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and REAPER MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for dsl_undo:
{
"version": "1",
"default": "deny",
"tools": {
"dsl_undo": {
"limits": [
{
"counter": "dsl_undo_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}dsl_undo 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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Undo the last action. Use for 'undo', 'undo that', 'go back', 'revert'. It is categorised as a Write tool in the REAPER MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the REAPER MCP Server MCP server in PolicyLayer and add a rule for dsl_undo: 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 MCP Server. Nothing to install.
dsl_undo 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 dsl_undo 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 dsl_undo. 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.
dsl_undo is provided by the REAPER MCP Server MCP server (shiehn/total-reaper-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 45 REAPER MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
45 REAPER MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.