Add a rehearsal mark in the live score.
AI agents use add_live_rehearsal_mark to create or update resources in Mcp Score — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mcp Score environment.
Adding a rehearsal mark is a standard music notation editing operation that creates new content in the score. While it modifies the score, the change is non-destructive and reversible, placing it squarely in the Write category rather than Execute or Destructive. The blast radius is minimal—misuse would only result in unwanted marks that can be easily removed.
From the tool's definition Tool adds a rehearsal mark to a live score, which modifies the score document by inserting a new notation element. The action is reversible (marks can be deleted or modified) and creates/modifies data without destructive side effects.
Documented attack patterns abuse exactly the kind of access add_live_rehearsal_mark gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Score, and nothing reaches the server without passing your rules. This is the rule we recommend for add_live_rehearsal_mark:
{
"version": "1",
"default": "deny",
"tools": {
"add_live_rehearsal_mark": {
"limits": [
{
"counter": "add_live_rehearsal_mark_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}add_live_rehearsal_mark 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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Add a rehearsal mark in the live score. It is categorised as a Write tool in the Mcp Score MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Mcp Score MCP server in PolicyLayer and add a rule for add_live_rehearsal_mark: 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 Mcp Score. Nothing to install.
add_live_rehearsal_mark 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 add_live_rehearsal_mark 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 add_live_rehearsal_mark. 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.
add_live_rehearsal_mark is provided by the Mcp Score MCP server (tskovlund/mcp-score). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Mcp Score, 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.
18 Mcp Score tools catalogued and risk-classified — across an index of 43,000+ MCP servers.