calculator

calculator is a skill for Claude Code, Codex from NVIDIA/SkillEvaluator. It costs 32 tokens per session (419 once invoked), scanned A, original, Apache-2.0.

A command-line calculator for arithmetic, percentages, and conversions between selected temperature, distance, weight, and length units.

In plain words
What is it for?
Use it for basic expressions, percentage calculations, and conversions between Celsius and Fahrenheit, miles and kilometres, kilograms and pounds, or metres and feet.
Why use it?
It provides checked calculations without external services and avoids the risks of evaluating arbitrary code.

Skill for Claude CodeCodex ✓ vendor

Written for no agent in particular: nothing here depends on one.

Good fit Use it for basic expressions, percentage calculations, and conversions between Celsius and…

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Install with agentmods
npx agentmods add skills/nvidia/skillevaluator/calculator
About the project

NVIDIA/SkillEvaluator is a framework for checking and evaluating AI-agent skills, which are instruction folders that extend an agent's behavior. Skill authors and agent developers use it to validate quality and security, detect overlap, generate evaluation data, and measure skills through live agent tests. The catalogue entries are skills for running these evaluation workflows.

NVIDIA/SkillEvaluator · 406 stars · on GitHub · docs.nvidia.com

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 NVIDIA/SkillEvaluator --skill calculator
Clone the repo
git clone --depth 1 https://github.com/NVIDIA/SkillEvaluator

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 calculator

README.md
[![agentmods](https://agentmods.dev/badge/skills/nvidia/skillevaluator/calculator.svg)](https://agentmods.dev/skills/nvidia/skillevaluator/calculator)
Your own site
<a href="https://agentmods.dev/skills/nvidia/skillevaluator/calculator"><img src="https://agentmods.dev/badge/skills/nvidia/skillevaluator/calculator.svg" alt="Measured on agentmods" height="20"></a>
Per session 32 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 419 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 $0.00032 $0.00419
Opus 5 $0.00016 $0.00210
Sonnet 5 $0.00006 $0.00084
Haiku 4.5 $0.00003 $0.00042

Measured 7d ago against content hash 0dabd9b89816, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

calculator 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 7d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/calc.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

src/skillevaluator/tier3/reference_skills/calculator/SKILL.md · 67 lines

What it actually says

Calculator

Evaluate math expressions and perform unit conversions from the command line.

Purpose

Provide a safe, sandboxed calculator for arithmetic expressions and common unit conversions without relying on eval() or external services.

Agent Instructions

  1. Read this SKILL.md to understand capabilities.
  2. Run scripts/calc.py with the user's expression or conversion.
  3. Return the computed result to the user.

Examples

Usage

# Arithmetic expressions
python scripts/calc.py "2 + 3 * 4"
python scripts/calc.py "(100 - 25) / 3"
python scripts/calc.py "2 ** 10"

# Percentage calculations
python scripts/calc.py "15% of 200"

# Unit conversions
python scripts/calc.py "100 celsius to fahrenheit"
python scripts/calc.py "5 miles to km"
python scripts/calc.py "10 kg to lbs"

Output

A single line with the result, e.g.:

Result: 14

For conversions:

100 celsius = 212.0 fahrenheit

Limitations

  • No symbolic algebra (no variables, no equations).
  • Only supports basic arithmetic operators: +, -, *, /, **, %, parentheses.
  • Unit conversions are limited to: celsius/fahrenheit, miles/km, kg/lbs, meters/feet.

Troubleshooting

Problem Fix
Invalid expression Check for unsupported operators or variables
Unknown conversion Use supported units: celsius, fahrenheit, miles, km, kg, lbs, meters, feet
Files

What ships with it

2 files 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. 7d ago First seen · 67 lines · 32 tokens per session scan A 0dabd9b89816

Subscribe to this mod's changes

calculator is a skill published in the GitHub repository NVIDIA/SkillEvaluator (406 stars, last pushed 3d ago), licensed Apache-2.0. It adds 32 tokens to every session and 419 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.

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