AI agents invoke open_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.
Opening a Grasshopper definition typically triggers loading and potentially running a parametric definition file in Grasshopper, which constitutes executing external code/scripts. The server context confirms it drives Grasshopper programmatically.
From the tool's definition Tool name 'open_grasshopper_definition' on a server that explicitly 'drives Grasshopper' and 'executes arbitrary Python scripts' with 'direct, programmatic control of Rhino 8'
Documented attack patterns abuse exactly the kind of access open_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 open_grasshopper_definition:
{
"version": "1",
"default": "deny",
"tools": {
"open_grasshopper_definition": {
"limits": [
{
"counter": "open_grasshopper_definition_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}open_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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open_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 open_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.
open_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 open_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 open_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.
open_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.