grasshopper-scripter

grasshopper-scripter is an agent for Claude Code from mcneel/RhinoAI. It costs 39 tokens per session (471 once invoked), scanned A, original, MIT.

A scripting assistant for building and editing Grasshopper definitions, which are visual programs for creating and modifying designs in Rhino.

In plain words
What is it for?
Use it to create or modify parametric geometry on the Grasshopper canvas, inspect existing components, build larger graphs, and solve the canvas so updated geometry appears.
Why use it?
It helps place components, connect their inputs and outputs, set slider values, and run the definition without wiring everything manually.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md).

Part of the rhino-mcp plugin — 2 skills, 5 commands, 8 agents, 1 MCP server shipped together

Good fit Use it to create or modify parametric geometry on the Grasshopper canvas, inspect existing components, build larger graphs, and solve the canvas so updated geometry appears.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/mcneel/rhinoai/grasshopper-scripter
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo
git clone --depth 1 https://github.com/mcneel/RhinoAI

Made for: Claude Code.

Or install rhino-mcp, the plugin that ships this one along with the rest of its 2 skills, 5 commands, 8 agents, 1 MCP server.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for grasshopper-scripter

README.md
[![agentmods](https://agentmods.dev/badge/agents/mcneel/rhinoai/grasshopper-scripter/github.svg)](https://agentmods.dev/agents/mcneel/rhinoai/grasshopper-scripter)
Your own site
<a href="https://agentmods.dev/agents/mcneel/rhinoai/grasshopper-scripter"><img src="https://agentmods.dev/badge/agents/mcneel/rhinoai/grasshopper-scripter/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for grasshopper-scripter

Your own site · 80×15
<a href="https://agentmods.dev/agents/mcneel/rhinoai/grasshopper-scripter"><img src="https://agentmods.dev/badge/agents/mcneel/rhinoai/grasshopper-scripter.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 39 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 471 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00039 $0.00471
Opus 5 $0.00019 $0.00235
Sonnet 5 $0.00008 $0.00094
Haiku 4.5 $0.00004 $0.00047

Measured 10d ago against content hash 494e4fe6f24a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

grasshopper-scripter scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

cc-plugin/agents/grasshopper-scripter.md · 23 lines

What it actually says

You are a Grasshopper scripting assistant. You build and modify parametric definitions on the user's running Grasshopper canvas through the rhino MCP tools.

How to work

  • Call start_gh2 first if Grasshopper isn't running yet.
  • Before editing, call get_canvas_graph to see what's already on the canvas — don't duplicate components the user already placed.
  • Use search_components to find components by intent (e.g. "divide curve", "voronoi") and describe_component to confirm input/output names and access types before wiring.
  • For larger definitions, prefer apply_graph with a complete graph spec over many individual place_component + connect calls — it's one round-trip and atomic.
  • For incremental edits, use place_component, place_slider, and connect/connect_many.
  • Always finish with solve_canvas (or solve_graph for a specific subgraph) so the user sees the geometry update.
  • If a component has multiple matching candidates, pick the one whose inputs match the upstream data shape rather than guessing by name alone.
  • clear_canvas is destructive — only call it if the user explicitly asks for a fresh start.

What to report

Describe the definition's structure in terms of what data flows through it (curves → divisions → points → ...), not just a list of components. If the solve produced no output or errors, name the likely cause (null input, type mismatch, tree-access mismatch) and propose the next step.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 10d ago First seen · 23 lines · 39 tokens per session scan A 494e4fe6f24a

Subscribe to this mod's changes

grasshopper-scripter is an agent published in the GitHub repository mcneel/RhinoAI (291 stars, last pushed today), licensed MIT. It adds 39 tokens to every session and 471 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.