AI agents invoke run_grasshopper_definition to trigger actions in GOLEM-3DMCP-Rhino-. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool executes Grasshopper definitions, which are parametric design scripts that can perform complex geometric operations, data processing, and side effects within Rhino. While the tool description is empty, the server context makes clear this is an Execute-class tool—it runs code/scripts rather than merely reading or writing data.
From the tool's definition Server description states it can 'drive Grasshopper' and 'execute arbitrary Python scripts, all through natural language.' The tool name 'run_grasshopper_definition' combined with the server's capability to execute arbitrary code indicates this tool triggers…
Documented attack patterns abuse exactly the kind of access run_grasshopper_definition gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and GOLEM-3DMCP-Rhino-, and nothing reaches the server without passing your rules. This is the rule we recommend for run_grasshopper_definition:
{
"version": "1",
"default": "deny",
"tools": {
"run_grasshopper_definition": {
"limits": [
{
"counter": "run_grasshopper_definition_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}run_grasshopper_definition stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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run_grasshopper_definition. It is categorised as a Execute tool in the GOLEM-3DMCP-Rhino- MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the GOLEM-3DMCP-Rhino- MCP server in PolicyLayer and add a rule for run_grasshopper_definition: 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 GOLEM-3DMCP-Rhino-. Nothing to install.
run_grasshopper_definition is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the run_grasshopper_definition 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 run_grasshopper_definition. 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.
run_grasshopper_definition is provided by the GOLEM-3DMCP-Rhino- MCP server (thekinghippopotamus/golem-3dmcp-rhino-). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from GOLEM-3DMCP-Rhino-, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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89 GOLEM-3DMCP-Rhino- tools catalogued and risk-classified — across an index of 43,000+ MCP servers.