sandbox-expr

sandbox-expr is a skill for Claude Code, Codex from nodetool-ai/nodetool. It costs 27 tokens per session (209 once invoked), scanned A, original, AGPL-3.0.

A sandbox skill for evaluating mathematical formulas in JavaScript code without using eval.

In plain words
What is it for?
Use it for calculations in Code nodes or CodeAct actions, such as evaluating user-provided expressions.
Why use it?
It lets code calculate formula results while avoiding direct execution of arbitrary JavaScript.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit Use it for calculations in Code nodes or CodeAct actions, such as evaluating user-provided expressions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/nodetool-ai/nodetool/sandbox-expr
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 nodetool-ai/nodetool --skill sandbox-expr
Clone the repo
git clone --depth 1 https://github.com/nodetool-ai/nodetool

Made for: Claude Code, Codex.

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 sandbox-expr

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/nodetool-ai/nodetool/sandbox-expr"><img src="https://agentmods.dev/badge/skills/nodetool-ai/nodetool/sandbox-expr.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 209 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 unknown 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 $0.00027 $0.00209
Opus 5 $0.00014 $0.00105
Sonnet 5 $0.00005 $0.00042
Haiku 4.5 $0.00003 $0.00021

Measured 6d ago against content hash a1e38c89b58b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

sandbox-expr 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 6d 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.

packages/sandbox-packs/sandbox-expr/SKILL.md · 29 lines

The source is not reproduced here

Licensed AGPL-3.0

The repository is licensed AGPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 6d ago First seen · 29 lines · 27 tokens per session scan A a1e38c89b58b

Subscribe to this mod's changes

sandbox-expr is a skill published in the GitHub repository nodetool-ai/nodetool (515 stars, last pushed yesterday), licensed AGPL-3.0. It adds 27 tokens to every session and 209 once invoked, about $0.0001 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 2026-09-03.

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