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Agent skill

Sandbox Dates

by nodetool-ai in nodetool-ai/nodetool

Date arithmetic, parsing and formatting inside a Code node or CodeAct action, with date-fns running in the guest

AGPL-3.0Auto-check passedDocuments & Office

Install Sandbox Dates

skills CLI
$ npx skills add nodetool-ai/nodetool --skill sandbox-dates -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install nodetool-ai/nodetool sandbox-dates --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/nodetool-ai/nodetool.git skills-src && mkdir -p .claude/skills && cp -r skills-src/packages/sandbox-packs/sandbox-dates .claude/skills/sandbox-dates && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
sandbox-dates
GitHub stars
560
Token cost
~464 tokens
SKILL.md length
184 words
Files
2
Skills in repo
127
Repo updated
First seen
Licence
AGPL-3.0

At a glance

Date arithmetic, parsing and formatting inside a Code node or CodeAct action, with date-fns running in the guest

  • Documents & Office work in your project
  • SKILL.md covers Arithmetic and comparison, Parsing and formatting and Gotchas
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Sandbox Dates is an agent skill from nodetool-ai/nodetool. Date arithmetic, parsing and formatting inside a Code node or CodeAct action, with date-fns running in the guest

Its SKILL.md is about 460 tokens, which your agent loads only when the skill is triggered. The skill folder holds 1 other file (for example `package.json`).

It sits in Documents & Office. The repository describes itself as: Agent-first Creative Workspace. The licence is AGPL-3.0.

When your agent uses it

  • Documents & Office work in your project

Example prompts

  • “/sandbox-dates”

What it can do on your machine

Read from SKILL.md and the folder at commit 58765d3. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are javascript).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Sandbox Dates loads about 464 tokens when it runs. Until then it costs about 32 tokens; SKILL.md has 184 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~32
When it runs · the whole SKILL.md, loaded when a task matches
~464

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from nodetool-ai/nodetool at commit 58765d3, republished under its AGPL-3.0 licence (© nodetool-ai). 184 words, ~464 tokens.

Download SKILL.mdSave it as .claude/skills/sandbox-dates/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
sandbox-dates
description
Date arithmetic, parsing and formatting inside a Code node or CodeAct action, with date-fns running in the guest

Dates in the sandbox

Specifier: @nodetool-ai/sandbox-dates. One module, date-fns's root export — around 250 named functions. There is no default export, so import the names you use.

Arithmetic and comparison

js
import { addDays, differenceInCalendarDays, isBefore } from "@nodetool-ai/sandbox-dates";

const due = addDays(new Date(inputs.startedAt), 30);
return { due: due.toISOString(), overdue: isBefore(due, new Date()), days: differenceInCalendarDays(due, new Date()) };

Parsing and formatting

js
import { parseISO, format, isValid } from "@nodetool-ai/sandbox-dates";

const when = parseISO(inputs.timestamp);
if (!isValid(when)) return { label: "unknown" };
return { label: format(when, "EEEE, d MMMM yyyy") };

format uses date-fns's own English locale tables, not Intl — which the guest does not have. That is why formatting works here at all, and it is also the limit: another language means another locale, and locales live at date-fns/locale, a subpath this pack does not publish.

Gotchas

  • UTC only. The guest runs with no time-zone database, so new Date() and every conversion behave as UTC. Anything zone-aware — "9 am in Berlin" — belongs on the host, not here.
  • Named imports only. import dates from "@nodetool-ai/sandbox-dates" gets you nothing; date-fns is pure ESM with no default export.
  • Import what you use. The bundle is about 176 KB and loads as one module per invocation, so a node that needs one comparison pays for all of it. For a single Date subtraction, plain arithmetic is cheaper.
  • No timers. setTimeout does not exist in the guest. date-fns needs none, but code around it must not either.

© nodetool-ai, AGPL-3.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file in packages/sandbox-packs/sandbox-dates of nodetool-ai/nodetool.

  • SKILL.md
  • package.json

Open the folder on GitHubat commit 58765d3

Compare with similar skills

Sandbox Dates next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Sandbox Dates compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Sandbox Dates this skillnodetool-ai/nodetool560—~464Automated safety check: PassAGPL-3.0
Markdown Article FormatterJimLiu/baoyu-skills26k6 repos~3.5kAutomated safety check: PassMIT
MarkitdownImCa0/just-laws78214 repos~3.2kAutomated safety check: NotesMIT
Obsidian MarkdownAtmosphere/atmosphere3.8k20 repos~1.3kAutomated safety check: PassApache-2.0
DOCXrvdbreemen/OTGW-firmware20733 repos~4.3kAutomated safety check: PassProprietary
Gzh Designisjiamu/gzh-design-skill3.9k1 repos~2.2kAutomated safety check: PassAGPL-3.0

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Categories

Questions about Sandbox Dates

What does Sandbox Dates do?

Date arithmetic, parsing and formatting inside a Code node or CodeAct action, with date-fns running in the guest. Sandbox Dates is an agent skill from nodetool-ai/nodetool.

When should I use Sandbox Dates?

Sandbox Dates fits situations like: documents & Office work in your project.

How do I install Sandbox Dates in Claude Code?

Run `npx skills add nodetool-ai/nodetool --skill sandbox-dates -a claude-code`. Or copy the skill folder (packages/sandbox-packs/sandbox-dates in nodetool-ai/nodetool) into .claude/skills/sandbox-dates in your project. Claude Code loads it when a task matches its description.

How do I install Sandbox Dates in Codex?

Run `npx skills add nodetool-ai/nodetool --skill sandbox-dates -a codex`. Or copy the skill folder (packages/sandbox-packs/sandbox-dates in nodetool-ai/nodetool) into .agents/skills/sandbox-dates in your project. Codex loads it when a task matches its description.

Can I use Sandbox Dates in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add nodetool-ai/nodetool --skill sandbox-dates -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/sandbox-dates, .gemini/skills/sandbox-dates, .github/skills/sandbox-dates and .opencode/skills/sandbox-dates in your project.

What does Sandbox Dates need to run?

SKILL.md names no scripts, command-line tools or credentials: Sandbox Dates is instructions for the agent only.

Does Sandbox Dates access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Sandbox Dates safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Sandbox Dates use?

Sandbox Dates is published under the AGPL-3.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Sandbox Dates use?

About 464 tokens (SKILL.md is roughly 1.9k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Sandbox Dates?

Skills that share tags, products or a category with Sandbox Dates: Markdown Article Formatter (JimLiu/baoyu-skills, 26k stars), Markitdown (ImCa0/just-laws, 782 stars), Obsidian Markdown (Atmosphere/atmosphere, 3.8k stars) and DOCX (rvdbreemen/OTGW-firmware, 207 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Sandbox Dates?

nodetool-ai (a GitHub organization) maintains it in nodetool-ai/nodetool, which has 560 GitHub stars. The repository holds 127 skills in this directory. The repository was last updated on October 9, 2026.

Source: nodetool-ai/nodetool on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.