monty-skill

monty-skill is a skill for Claude Code from zeenie-ai/OpenCompany. It costs 42 tokens per session (1,251 once invoked), scanned A, original, MIT.

A Python runner that executes code in an isolated environment with enforced time and memory limits. It is designed for code that should not have ordinary access to the host computer.

In plain words
What is it for?
It helps run small Python programs with controlled time, memory, and optional host capabilities such as explicitly granted access.
Why use it?
It reduces the risk that untrusted Python code will access the system or run without bounds.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Good fit It helps run small Python programs with controlled time, memory, and optional host capabilities such as explicitly granted access.

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Install with agentmods
npx agentmods add skills/zeenie-ai/opencompany/monty-skill
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.

Any agent
npx skills add zeenie-ai/OpenCompany --skill monty-skill
Clone the repo
git clone --depth 1 https://github.com/zeenie-ai/OpenCompany

Made for: Claude Code.

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 monty-skill

README.md
[![agentmods](https://agentmods.dev/badge/skills/zeenie-ai/opencompany/monty-skill/github.svg)](https://agentmods.dev/skills/zeenie-ai/opencompany/monty-skill)
Your own site
<a href="https://agentmods.dev/skills/zeenie-ai/opencompany/monty-skill"><img src="https://agentmods.dev/badge/skills/zeenie-ai/opencompany/monty-skill/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 monty-skill

Your own site · 80×15
<a href="https://agentmods.dev/skills/zeenie-ai/opencompany/monty-skill"><img src="https://agentmods.dev/badge/skills/zeenie-ai/opencompany/monty-skill.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,251 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00042 $0.01251
Opus 5 $0.00021 $0.00626
Sonnet 5 $0.00008 $0.00250
Haiku 4.5 $0.00004 $0.00125

Measured 13d ago against content hash c43899d0f040, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

monty-skill 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 13d 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.

server/skills/coding_agent/monty-skill/SKILL.md · 117 lines

How it starts

The opening of the file, as written. The whole thing — 117 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Sandboxed Python (Monty) Tool

Execute Python in a deny-by-default sandbox powered by Pydantic Monty — a minimal Python interpreter written in Rust. Unlike the python_code tool (CPython exec with a restricted namespace), Monty enforces wall-clock and memory limits and grants zero host access unless you explicitly request it.

Prefer this tool when running code you don't fully trust, or when you need guaranteed time/memory bounds. Use python_code instead when you need libraries Monty doesn't support (e.g. random, collections) or language features it lacks (classes, generators).

How It Works

Connect the Monty Executor node to an agent's input-tools handle. The LLM calls the sandboxed_python tool with code (and optionally capabilities, timeout, max_memory_mb).

Schema Fields

Field Type Required Default Description
code string Yes Python code to run in the sandbox
timeout int No 30 Max wall-clock seconds (1–600), enforced
max_memory_mb int No 256 Max memory in MB (16–2048), enforced
capabilities string[] No [] Host grants to enable (see below); empty = no host access

Inputs & Output

  • input_data — a dict of upstream node outputs is available as the variable input_data. Read with input_data.get('someNode', {}).
  • Return a result by making it the last expression in your code (e.g. a final line that is just output or a dict literal).
  • print(...) output is captured and returned as console_output.

Supported Python Subset

Works Does NOT work
def, closures, lambda class definitions
if / for / while yield / generators
try / except with statements (without a workspace mount)
list / dict / set comprehensions match / case
f-strings import random, import collections, import os
async def / await arbitrary third-party packages
import math, import json, import re

Read the full file on GitHub · 117 lines

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. 13d ago First seen · 117 lines · 42 tokens per session scan A c43899d0f040

Subscribe to this mod's changes

monty-skill is a skill published in the GitHub repository zeenie-ai/OpenCompany (883 stars, last pushed today), licensed MIT. It adds 42 tokens to every session and 1,251 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.