Agent skill

Sandbox YAML

Read and write YAML inside a Code node or CodeAct action, with js-yaml running in the guest

AGPL-3.0Auto-check passedDocuments & Office

Install Sandbox YAML

skills CLI

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

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

GitHub CLI

$ gh skill install nodetool-ai/nodetool sandbox-yaml --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-yaml .claude/skills/sandbox-yaml && 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/

Paste into Claude Code

Install the "sandbox-yaml" agent skill from https://github.com/nodetool-ai/nodetool/tree/main/packages/sandbox-packs/sandbox-yaml into .claude/skills/sandbox-yaml/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "sandbox-yaml", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/nodetool-ai/nodetool/tree/main/packages/sandbox-packs/sandbox-yaml

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add nodetool-ai/nodetool --skill sandbox-yaml -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install nodetool-ai/nodetool sandbox-yaml --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

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

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "sandbox-yaml" agent skill from https://github.com/nodetool-ai/nodetool/tree/main/packages/sandbox-packs/sandbox-yaml into .agents/skills/sandbox-yaml/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "sandbox-yaml", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add nodetool-ai/nodetool --skill sandbox-yaml -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install nodetool-ai/nodetool sandbox-yaml --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

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

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "sandbox-yaml" agent skill from https://github.com/nodetool-ai/nodetool/tree/main/packages/sandbox-packs/sandbox-yaml into .cursor/skills/sandbox-yaml/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "sandbox-yaml", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/nodetool-ai/nodetool.git --path packages/sandbox-packs/sandbox-yaml

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add nodetool-ai/nodetool --skill sandbox-yaml -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install nodetool-ai/nodetool sandbox-yaml --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

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

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "sandbox-yaml" agent skill from https://github.com/nodetool-ai/nodetool/tree/main/packages/sandbox-packs/sandbox-yaml into .gemini/skills/sandbox-yaml/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "sandbox-yaml", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install nodetool-ai/nodetool sandbox-yaml

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add nodetool-ai/nodetool --skill sandbox-yaml -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

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

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "sandbox-yaml" agent skill from https://github.com/nodetool-ai/nodetool/tree/main/packages/sandbox-packs/sandbox-yaml into .github/skills/sandbox-yaml/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "sandbox-yaml", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add nodetool-ai/nodetool --skill sandbox-yaml -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install nodetool-ai/nodetool sandbox-yaml --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

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

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "sandbox-yaml" agent skill from https://github.com/nodetool-ai/nodetool/tree/main/packages/sandbox-packs/sandbox-yaml into .opencode/skills/sandbox-yaml/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "sandbox-yaml", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: sandbox-yaml
GitHub stars: 560
Token cost: ~450 tokens
SKILL.md length: 223 words
Files: 2
Skills in repo: 127
Repo updated: Oct 10, 2026
First seen: Oct 7, 2026
Licence: AGPL-3.0

At a glance

Read and write YAML inside a Code node or CodeAct action, with js-yaml running in the guest

Documents & Office work in your project
SKILL.md covers load — YAML text to a value, dump — a value to YAML text and Gotchas
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Sandbox YAML is an agent skill from nodetool-ai/nodetool. Read and write YAML inside a Code node or CodeAct action, with js-yaml running in the guest

Its SKILL.md is about 450 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-yaml”

What it can do on your machine

Read from SKILL.md and the folder at commit 339f069. 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 YAML loads about 450 tokens when it runs. Until then it costs about 26 tokens; SKILL.md has 223 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~26
When it runs · the whole SKILL.md, loaded when a task matches: ~450

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 339f069, republished under its AGPL-3.0 licence (© nodetool-ai). 223 words, ~450 tokens.

Download SKILL.mdSave it as .claude/skills/sandbox-yaml/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.

name: sandbox-yaml
description: Read and write YAML inside a Code node or CodeAct action, with js-yaml running in the guest

YAML in the sandbox

Specifier: @nodetool-ai/sandbox-yaml. One module, the js-yaml root export. Import it at the top of the body.

load — YAML text to a value

import yaml from "@nodetool-ai/sandbox-yaml";

const config = yaml.load(inputs.text);
return { name: config.name, replicas: config.replicas };

load reads one document and throws a YAMLException with a line and column on malformed input. Multi-document files go through loadAll, which returns an array.

dump — a value to YAML text

import yaml from "@nodetool-ai/sandbox-yaml";

return { text: yaml.dump({ name: inputs.name, tags: inputs.tags }, { indent: 2 }) };

dump throws on a cyclic structure unless you pass { noRefs: false }, and on a value it cannot represent (a function, a symbol).

Gotchas

Everything runs in the guest. The 64 MB guest heap holds your input text, the parse tree, and the returned value at once. A file of a few megabytes is fine; a hundred megabytes is not.
No timers, no I/O. The guest has no setTimeout, no filesystem, and no Node builtins. js-yaml needs none of them — that is why it is admitted — but code you write around it must not reach for them either.
The safe schema is not the default. yaml.load uses DEFAULT_SCHEMA, which resolves tags such as !!timestamp. For input from a stranger, pass { schema: yaml.FAILSAFE_SCHEMA } and get strings, arrays, and objects only.
This pack is the only route to YAML. There is no data.parseYaml global any more; every library the sandbox offers is an importable module, and this is the one for YAML. A node that needs it declares it.

Files

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

SKILL.md
package.json

Open the folder on GitHubat commit 339f069

Compare with similar skills

Sandbox YAML 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 YAML compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Sandbox YAML this skillnodetool-ai/nodetool	560	—	~450	Automated safety check: Pass	AGPL-3.0	yesterday
Markdown Article FormatterJimLiu/baoyu-skills	27k	6 repos	~3.5k	Automated safety check: Pass	MIT	1 mo ago
MarkitdownImCa0/just-laws	781	14 repos	~3.2k	Automated safety check: Notes	MIT	3 days ago
Obsidian MarkdownAtmosphere/atmosphere	3.8k	20 repos	~1.3k	Automated safety check: Pass	Apache-2.0	2 days ago
DOCXrvdbreemen/OTGW-firmware	207	33 repos	~4.3k	Automated safety check: Pass	Proprietary	4 days ago
Word Document Reader and WriterHKUDS/DeepTutor	41k	—	~2.5k	Automated safety check: Pass	Apache-2.0	3 days ago

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Questions about Sandbox YAML

What does Sandbox YAML do?

Read and write YAML inside a Code node or CodeAct action, with js-yaml running in the guest. Sandbox YAML is an agent skill from nodetool-ai/nodetool.

When should I use Sandbox YAML?

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

How do I install Sandbox YAML in Claude Code?

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

How do I install Sandbox YAML in Codex?

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

Can I use Sandbox YAML 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-yaml -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-yaml, .gemini/skills/sandbox-yaml, .github/skills/sandbox-yaml and .opencode/skills/sandbox-yaml in your project.

What does Sandbox YAML need to run?

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

Does Sandbox YAML 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 YAML 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 YAML use?

Sandbox YAML 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 YAML use?

About 450 tokens (SKILL.md is roughly 1.8k 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 YAML?

Skills that share tags, products or a category with Sandbox YAML: Markdown Article Formatter (JimLiu/baoyu-skills, 27k stars), Markitdown (ImCa0/just-laws, 781 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 YAML?

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 10, 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.

Install Sandbox YAML

Facts

At a glance

What it does

When your agent uses it

Example prompts

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

YAML in the sandbox

load — YAML text to a value

dump — a value to YAML text

Gotchas

Files

Compare with similar skills

Similar skills

More from nodetool-ai/nodetool

Related

Questions about Sandbox YAML