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Agent skill

Prototyping When And What

by hashgraph-online in hashgraph-online/awesome-codex-plugins

A skill your agent uses when deciding what to prototype, what fidelity to use, and when to stop prototyping and ship.

Apache-2.0Auto-check passedDevelopment

Install Prototyping When And What

skills CLI
$ npx skills add hashgraph-online/awesome-codex-plugins --skill prototyping-when-and-what -a claude-code

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

GitHub CLI
$ gh skill install hashgraph-online/awesome-codex-plugins prototyping-when-and-what --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/hashgraph-online/awesome-codex-plugins.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/HDeibler/universal-design-principles/plugins/process-and-robustness-principles/skills/prototyping-when-and-what .claude/skills/prototyping-when-and-what && 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
prototyping-when-and-what
GitHub stars
1.3k
Token cost
~1.3k tokens
SKILL.md length
657 words
Files
2 (incl. references)
Skills in repo
716
Repo updated
First seen
Licence
Apache-2.0

At a glance

A skill your agent uses when deciding what to prototype, what fidelity to use, and when to stop prototyping and ship.

  • Works in 4 steps: The "cheapest fidelity" rule. Pick the… → The "what would change?" check. Before… → The disposability check. If you'd be sad… → …
  • Deciding what to prototype
  • SKILL.md covers What to prototype, What NOT to prototype, Picking fidelity and When to stop prototyping, plus 5 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Prototyping When And What is an agent skill from hashgraph-online/awesome-codex-plugins. Use this skill when deciding what to prototype, what fidelity to use, and when to stop prototyping and ship. Trigger when planning research, scoping a design phase, or facing pressure to "stop prototyping and just build it." Sub-aspect of prototyping; read that first.

Its SKILL.md is about 1.3k tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/when-to-stop.md`).

It sits in Development, covering Prototyping. The repository describes itself as: A curated list of awesome OpenAI Codex / ChatGPT plugins, skills, and resources. The 1 Codex Marketplace. See live plugins at: https://hol.org/plugins/best-codex-plugins. The licence is Apache-2.0.

When your agent uses it

  • Deciding what to prototype
  • What fidelity to use
  • When to stop prototyping and ship
  • Planning research

Example prompts

  • “stop prototyping and just build it.”
  • “/prototyping-when-and-what”

Workflow steps

4 steps, taken from the first numbered list in SKILL.md.

  1. The "cheapest fidelity" rule. Pick the cheapest fidelity that answers the question.
  2. The "what would change?" check. Before building a prototype, ask: if the prototype reveals X, what will I do? If Y, what? If you can't…
  3. The disposability check. If you'd be sad to throw the prototype away, you over-invested.
  4. The stakeholder-framing audit. Is everyone clear this is a prototype? If not, expectations will diverge from reality.

What it can do on your machine

Read from SKILL.md and the folder at commit 3e1456a. 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.

    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

Prototyping When And What loads about 1.3k tokens when it runs, and up to ~1.9k if it reads all its reference files. Until then it costs about 74 tokens; SKILL.md has 657 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~74
When it runs · the whole SKILL.md, loaded when a task matches
~1.3k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~1.9k

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 hashgraph-online/awesome-codex-plugins at commit 3e1456a, republished under its Apache-2.0 licence (© hashgraph-online). 657 words, ~1,334 tokens.

Download SKILL.mdSave it as .claude/skills/prototyping-when-and-what/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
prototyping-when-and-what
description
Use this skill when deciding what to prototype, what fidelity to use, and when to stop prototyping and ship. Trigger when planning research, scoping a design phase, or facing pressure to "stop prototyping and just build it." Sub-aspect of `prototyping`; read that first.

Picking what and when to prototype

Prototyping has costs (time, opportunity, sometimes confusion). Picking the right thing to prototype, at the right fidelity, at the right moment, is how teams get the benefits without the costs.

What to prototype

Three categories of question prototypes answer well:

Risky assumptions

Things you're not sure will work. The riskier the assumption, the more valuable the prototype.

  • "Users will understand this new flow" — prototype + user test.
  • "This algorithm will be fast enough at production scale" — throwaway performance prototype.
  • "Customers will pay for this feature" — concierge MVP or smoke test.
Disputed decisions

When stakeholders disagree, prototypes resolve faster than discussion.

  • Designer vs. engineering on flow complexity.
  • PM vs. design on feature scope.
  • Marketing vs. design on visual direction.
High-investment decisions

When the cost of being wrong is high — time, money, brand — invest in prototyping to reduce risk.

  • New product launches.
  • Architectural changes.
  • Brand redesigns.

What NOT to prototype

  • Well-understood patterns. Don't prototype the placement of a Save button on a CRUD form.
  • Decisions you'd make the same way regardless of the prototype's outcome. If you'd ship the favorite anyway, prototyping the alternative is wasted.
  • Things you can't act on. Prototyping a feature you won't have engineering to build is theater.

Picking fidelity

The fidelity-to-question match (covered more in iteration-prototype-fidelity):

QuestionFidelity
"Does this structure make sense?"Sketch / wireframe
"Is this visual direction right?"Mockup
"Does the flow work for users?"Clickable prototype
"Will it be fast enough?"Code prototype
"Will users adopt it at scale?"Production beta

Going higher than necessary wastes time and risks anchoring stakeholders.

When to stop prototyping

A common failure: indefinite prototyping that never ships. Signals it's time to stop:

  • The current iteration is producing diminishing returns.
  • The remaining unknowns are best resolved by real users in production.
  • Stakeholders are reviewing prototypes that look final.
  • The next "iteration" is essentially the build phase.

The discipline: define explicit "good enough to ship" criteria before starting to prototype. When the criteria are met, ship.

Communication with stakeholders

Stakeholders often see polished prototypes as nearly-finished products. The artificial reality problem in stakeholder form.

Communication patterns:

  • Label fidelity explicitly. "This is a low-fidelity prototype" prefacing demos.
  • Name what's not yet built. "The visual style is placeholder; the interaction is what we're testing."
  • Set expectations for the timeline. "From here to production is X weeks."

Without this framing, stakeholders form unrealistic expectations.

Show full SKILL.md (261 more words)Show less

Common patterns

Spike + commit

Pre-engineering: a 1–3 day technical spike to validate feasibility. Then commit to building if the spike succeeds.

Test-then-design

Pre-design: usability test of competitor products or prior versions to gather data; then design informed by the data.

Prototype-then-spec

Pre-spec: build a prototype; specifications come from what the prototype reveals. The spec describes the working prototype rather than predicting it.

Continuous prototyping (modern agile)

Each sprint produces something testable. Each release prototypes the next. The line between prototype and product blurs.

Anti-patterns

  • Prototyping without a question. Building because "we should make a prototype" rather than to answer something specific.
  • Endless iteration. Prototyping past the point of diminishing returns; never shipping.
  • Production-quality prototypes. Building prototypes to production code quality; the cost of throwaway evaporates.
  • Stakeholder confusion. Showing polished prototypes without framing; stakeholders think it's done.
  • Fidelity creep. Starting low-fi; gradually polishing; ending with a high-fi prototype that took as long as the actual product would have.

Heuristics

  1. The "cheapest fidelity" rule. Pick the cheapest fidelity that answers the question.
  2. The "what would change?" check. Before building a prototype, ask: if the prototype reveals X, what will I do? If Y, what? If you can't name actions, the prototype isn't worth building.
  3. The disposability check. If you'd be sad to throw the prototype away, you over-invested.
  4. The stakeholder-framing audit. Is everyone clear this is a prototype? If not, expectations will diverge from reality.
  • prototyping (parent).
  • prototyping-concept-throwaway-evolutionary — picking the kind.
  • iteration — prototypes power iteration.
  • iteration-prototype-fidelity — fidelity selection in detail.
  • 80-20-rule — prototype the 20% that matters most.

© hashgraph-online, Apache-2.0. 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 (references) in plugins/HDeibler/universal-design-principles/plugins/process-and-robustness-principles/skills/prototyping-when-and-what of hashgraph-online/awesome-codex-plugins.

  • SKILL.md
  • references/when-to-stop.md

Open the folder on GitHubat commit 3e1456a

Compare with similar skills

Prototyping When And What 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.

Prototyping When And What compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Prototyping When And What this skillhashgraph-online/awesome-codex-plugins1.3k—~1.3kAutomated safety check: PassApache-2.0
Native Feel Cross Platform Desktopyetone/native-feel-skill1.9k1 repos~1.5kAutomated safety check: PassMIT
Compound Engineering PrototypeEveryInc/compound-engineering-plugin25k—~1.9kAutomated safety check: PassMIT
Collaborating With CodexGuDaStudio/collaborating-with-codex1321 repos~712Automated safety check: PassMIT
Digikeyaklofas/kicad-happy1.4k1 repos~4.5kAutomated safety check: PassMIT
Collaborating With Geminihaoyu-haoyu/Multi-AI-Workflow109—~521Automated safety check: PassMIT

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Categories

Questions about Prototyping When And What

What does Prototyping When And What do?

A skill your agent uses when deciding what to prototype, what fidelity to use, and when to stop prototyping and ship. Prototyping When And What is an agent skill from hashgraph-online/awesome-codex-plugins. Use this skill when deciding what to prototype, what fidelity to use, and when to stop prototyping and ship.

When should I use Prototyping When And What?

Prototyping When And What fits situations like: deciding what to prototype; what fidelity to use; when to stop prototyping and ship; planning research.

How do I install Prototyping When And What in Claude Code?

Run `npx skills add hashgraph-online/awesome-codex-plugins --skill prototyping-when-and-what -a claude-code`. Or copy the skill folder (plugins/HDeibler/universal-design-principles/plugins/process-and-robustness-principles/skills/prototyping-when-and-what in hashgraph-online/awesome-codex-plugins) into .claude/skills/prototyping-when-and-what in your project. Claude Code loads it when a task matches its description.

How do I install Prototyping When And What in Codex?

Run `npx skills add hashgraph-online/awesome-codex-plugins --skill prototyping-when-and-what -a codex`. Or copy the skill folder (plugins/HDeibler/universal-design-principles/plugins/process-and-robustness-principles/skills/prototyping-when-and-what in hashgraph-online/awesome-codex-plugins) into .agents/skills/prototyping-when-and-what in your project. Codex loads it when a task matches its description.

Can I use Prototyping When And What 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 hashgraph-online/awesome-codex-plugins --skill prototyping-when-and-what -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/prototyping-when-and-what, .gemini/skills/prototyping-when-and-what, .github/skills/prototyping-when-and-what and .opencode/skills/prototyping-when-and-what in your project.

What does Prototyping When And What need to run?

SKILL.md names no scripts, command-line tools or credentials: Prototyping When And What is instructions for the agent only.

Does Prototyping When And What 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 Prototyping When And What 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 Prototyping When And What use?

Prototyping When And What is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Prototyping When And What use?

About 1.3k tokens (SKILL.md is roughly 5.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 571 tokens, read only when the agent opens those files.

What are the alternatives to Prototyping When And What?

Skills that share tags, products or a category with Prototyping When And What: Native Feel Cross Platform Desktop (yetone/native-feel-skill, 1.9k stars), Compound Engineering Prototype (EveryInc/compound-engineering-plugin, 25k stars), Collaborating With Codex (GuDaStudio/collaborating-with-codex, 132 stars) and Digikey (aklofas/kicad-happy, 1.4k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Prototyping When And What?

hashgraph-online (a GitHub organization) maintains it in hashgraph-online/awesome-codex-plugins, which has 1,267 GitHub stars. The repository holds 716 skills in this directory. The repository was last updated on October 10, 2026.

Source: hashgraph-online/awesome-codex-plugins on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.