AI agents use set_gp_key_signature to create or update resources in Guitar Pro — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Guitar Pro environment.
Key signature is a musical parameter that can be changed or reverted, making this a Write operation rather than Destructive. The empty description lowers confidence slightly, but the tool name and sibling context (all modification tools on a Guitar Pro manipulator server) indicate it modifies rather than deletes data.
From the tool's definition Tool name is set_gp_key_signature. This tool modifies a Guitar Pro file by setting the key signature of the track, which is a reversible change to file content (analogous to sibling tools like add_gp_measure, add_gp_note that create/modify data).
Documented attack patterns abuse exactly the kind of access set_gp_key_signature gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Guitar Pro, and nothing reaches the server without passing your rules. This is the rule we recommend for set_gp_key_signature:
{
"version": "1",
"default": "deny",
"tools": {
"set_gp_key_signature": {
"limits": [
{
"counter": "set_gp_key_signature_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}set_gp_key_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_gp_key_signature. It is categorised as a Write tool in the Guitar Pro MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Guitar Pro MCP server in PolicyLayer and add a rule for set_gp_key_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 Guitar Pro. Nothing to install.
set_gp_key_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_gp_key_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_gp_key_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_gp_key_signature is provided by the Guitar Pro MCP server (wegitor/guitar-pro-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Guitar Pro, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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35 Guitar Pro tools catalogued and risk-classified — across an index of 43,000+ MCP servers.