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 agentmods add skills/shinpr/nautilus/prototype-guidenpx skills add shinpr/nautilus --skill prototype-guidegit clone --depth 1 https://github.com/shinpr/nautilusWhat 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 | $0.00039 | $0.00412 |
| Opus 5 | $0.00019 | $0.00206 |
| Sonnet 5 | $0.00008 | $0.00082 |
| Haiku 4.5 | $0.00004 | $0.00041 |
Grade A, and why
prototype-guide 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 2d 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.
How it starts
The opening of the file, as written. The whole thing — 41 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Prototype Guide
Purpose
A prototype makes one product decision observable before delivery. Apply product evidence and design decisions that affect that observation; leave unrelated implementation choices to the generator.
Required Context
Start from:
- the hypothesis and its success/failure criteria;
- the persona and scenario when they change behavior or evaluation;
- the product and design sources selected by
references/prototype-quality.md.
Classify a missing input as blocking only when it controls the tested flow or interpretation. Name the missing decision and the evidence that would resolve it.
Shared Prototype Contract
- Focus on one validation decision. Combine hypotheses only when the same interaction and evidence resolve them together.
- Make the critical flow, consequences, and relevant recovery behavior observable.
- Use domain-realistic content and data rather than generic placeholders.
- Apply the highest-priority available design source instead of re-inferring existing decisions.
- Implement the states that can occur and affect the validation decision. Report each implemented trigger and any non-obvious exclusion whose absence could change evaluation.
- Keep the visible UI product-native; carry test setup and evaluation evidence in the completion report.
- Preserve the artifacts needed to evaluate, reproduce, or reuse the result.
Reference Routing
- WHEN generating or evaluating a prototype artifact: read
references/prototype-quality.mdand apply every applicable criterion. - WHEN exporting a prompt for an external generator: also read
references/prototype-prompt-guide.mdand the selected platform template. - WHEN product-specific usability, persona, state, or accessibility decisions are needed: load
design-perspective.
Scope Boundary
This skill owns prototype quality and prompt construction. recipe-validate owns the validation lifecycle and hypothesis record. recipe-prototype-prompt owns explicit external prompt export. The prototype generator owns the HTML artifact.
What ships with it
4 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.
- 2d ago First seen · 41 lines · 39 tokens per session scan A 25458441be48
prototype-guide is a skill published in the GitHub repository shinpr/nautilus (4 stars, last pushed 4d ago), licensed MIT. It adds 39 tokens to every session and 412 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 2026-08-31.
Other skills, from other repositories
blueprint-standards
Defines structural design artifact formats — information architecture, user flows, content model, brand direction, and AI interaction model. Use when creating or reviewing structural design documents that precede prototype generation.
recipe-blueprint
Define structural design foundation — information architecture, user flows, content model, brand direction, and AI interaction model — from validated opportunities and hypotheses.
recipe-refine-visuals
Optional side-workflow for design experts to refine Concrete Tokens in brand-direction.md when a named downstream consumer needs reproducible values.
design-perspective
Integrates design principles, WCAG 2.2 AA accessibility, persona context, and state design into product decisions. Use when reviewing UX decisions, checking accessibility, applying design principles, or ensuring state coverage in acceptance criteria.
prototype-guide
Generates self-contained HTML prototypes with design context from project files. Read design principles, personas, and hypothesis files, then produce a working prototype for Usability and Value risk validation. Use when creating prototypes or validating through tangible artifacts.
idea-clarifier
Use this skill when the user has a product idea, feature concept, startup direction, vague requirement, or asks for a PRD before the idea is clear. Run a ruthless pre-launch clarification workflow: first challenge user/problem/value/MVP as a senior product manager, then challenge market/business/growth/ROI as a…