This record as markdown: /tools/hybridlabor-api-aos/open-grasshopper-definition.md
What open_grasshopper_definition does on Aos
AI agents invoke open_grasshopper_definition to trigger actions in Aos. 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.
Why open_grasshopper_definition is rated High
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'
Attacks that exploit this kind of access
The rule that runs open_grasshopper_definition safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Aos, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For open_grasshopper_definition, this is the rule to start with:
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.
The button opens the PolicyLayer dashboard: create your workspace, connect Aos, apply this rule, and every open_grasshopper_definition call is checked against it from then on.
Questions about open_grasshopper_definition
open_grasshopper_definition is a execute tool on the Aos MCP server. It is categorised as a Execute tool in the Aos MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Aos 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 Aos. 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 Aos MCP server (@hybridlabor-api/aos). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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