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.
npx skills add HK-hub/AgentSkills --skill playgroundgit clone --depth 1 https://github.com/HK-hub/AgentSkillsWrote 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.
[](https://agentmods.dev/skills/hk-hub/agentskills/playground)<a href="https://agentmods.dev/skills/hk-hub/agentskills/playground"><img src="https://agentmods.dev/badge/skills/hk-hub/agentskills/playground/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.
<a href="https://agentmods.dev/skills/hk-hub/agentskills/playground"><img src="https://agentmods.dev/badge/skills/hk-hub/agentskills/playground.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00053 | $0.00826 |
| Opus 5.5 | $0.00021 | $0.00330 |
| Sonnet 5.5 | $0.00011 | $0.00165 |
| Haiku 4.5 | $0.00005 | $0.00083 |
Grade A, and why
playground 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 1mo 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.
This is a copy
100% identical to playground — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 77 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Playground Builder
A playground is a self-contained HTML file with interactive controls on one side, a live preview on the other, and a prompt output at the bottom with a copy button. The user adjusts controls, explores visually, then copies the generated prompt back into Claude.
When to use this skill
When the user asks for an interactive playground, explorer, or visual tool for a topic — especially when the input space is large, visual, or structural and hard to express as plain text.
How to use this skill
- Identify the playground type from the user's request
- Load the matching template from
templates/:templates/design-playground.md— Visual design decisions (components, layouts, spacing, color, typography)templates/data-explorer.md— Data and query building (SQL, APIs, pipelines, regex)templates/concept-map.md— Learning and exploration (concept maps, knowledge gaps, scope mapping)templates/document-critique.md— Document review (suggestions with approve/reject/comment workflow)templates/diff-review.md— Code review (git diffs, commits, PRs with line-by-line commenting)templates/code-map.md— Codebase architecture (component relationships, data flow, layer diagrams)
- Follow the template to build the playground. If the topic doesn't fit any template cleanly, use the one closest and adapt.
- Open in browser. After writing the HTML file, run
open <filename>.htmlto launch it in the user's default browser.
Core requirements (every playground)
- Single HTML file. Inline all CSS and JS. No external dependencies.
- Live preview. Updates instantly on every control change. No "Apply" button.
- Prompt output. Natural language, not a value dump. Only mentions non-default choices. Includes enough context to act on without seeing the playground. Updates live.
- Copy button. Clipboard copy with brief "Copied!" feedback.
- Sensible defaults + presets. Looks good on first load. Include 3-5 named presets that snap all controls to a cohesive combination.
- Dark theme. System font for UI, monospace for code/values. Minimal chrome.
What ships with it
6 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.
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.
- 1mo ago First seen · 77 lines · 53 tokens per session scan A 521a3d62211e
playground is a skill published in the GitHub repository HK-hub/AgentSkills (6 stars, last pushed 2mo ago), licensed MIT. It adds 53 tokens to every session and 826 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to playground, differing in 0 lines, and is treated as a copy.
Other skills, from other repositories
spec-brainstorm
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spec-plan
Write approved implementation plans in one of two modes. Explicit Inline mode creates a conversational plan for bounded work. Spec-backed Plan converts an approved design.md into plan.json. Both modes stop after producing their plan output. Trigger after atelier-orchestrator selects a mode, when the user asks to plan…
spec-implement
Continue an approved Spec-backed workflow when the user says "implement", "go", "start", or "do it". After Codex Plan Mode, persist the next missing design.md or plan.json artifact and stop. When both artifacts exist, execute plan.json with TDD and report between batches.
atelier-orchestrator
Skill routing and workflow orchestration. Selects Inline Plan or Spec-backed Plan, routes to the correct workflow skill, and manages transitions between phases. Use when starting any conversation or task to determine which planning mode and skill apply.
oracle-codebase-design
Shared vocabulary and principles for designing deep modules. Use when designing or changing a module's interface, deciding where a seam goes, handling untrusted input at the edges, choosing the level to test at, naming modules, or making code more testable. Also use when another skill needs the deep-module vocabulary.
atelier-setup
Configure a repository for Atelier's development workflow. Use only when explicitly invoked; inspect existing guidance, issue-tracker and domain-document conventions, preview the proposed configuration, and write only after approval. It does not install Atelier or initialize external tooling.