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/modernweb-dev/rocket/modern-web-guidancenpx skills add modernweb-dev/rocket --skill modern-web-guidancegit clone --depth 1 https://github.com/modernweb-dev/rocketWrote 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/modernweb-dev/rocket/modern-web-guidance)<a href="https://agentmods.dev/skills/modernweb-dev/rocket/modern-web-guidance"><img src="https://agentmods.dev/badge/skills/modernweb-dev/rocket/modern-web-guidance.svg" alt="Measured on agentmods" 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 | $0.00233 | $0.01291 |
| Opus 5 | $0.00117 | $0.00646 |
| Sonnet 5 | $0.00047 | $0.00258 |
| Haiku 4.5 | $0.00023 | $0.00129 |
Grade A, and why
modern-web-guidance 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 4d 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 modern-web-guidance — 16 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 — 115 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Modern Web Guidance
A skill to search for specific web development use cases and retrieve their corresponding best practice guides.
When to use
Must use this skill:
- At the start of implementing any web feature.
- Before creating a new component, to check if a standardized pattern already exists.
- To avoid implementing ad-hoc solutions or loading large dependencies unnecessarily.
Usage Instructions
Step 1. Search Use Cases
Search with an action-oriented query summarizing what you want to achieve using the search command. Run modern-web-guidance directly with npx.
npx -y modern-web-guidance@latest search "<query>" --skill-version 2026_05_16-c5e7870
Example Output:
[
{
"id": "optimize-image-priority",
"description": "Optimize the loading priority of Largest Contentful Paint (LCP) candidate images.",
"category": "performance",
"featuresUsed": [ "Fetch priority" ],
"tokenCount": 985,
"similarity": 0.7289
},
{
"id": "defer-rendering-heavy-content",
"description": "Reduce rendering times in content-heavy web pages by deferring rendering for offscreen content.",
"category": "performance",
"featuresUsed": [ "content-visibility", "hidden=\"until-found\"" ],
"tokenCount": 1250,
"similarity": 0.6961
}
]
Note: If search results are vague, return no matches, or show low similarity scores, run the
listcommand to browse all guides:npx -y modern-web-guidance@latest list
Step 2. Retrieve Best Practices
Once you have a relevant id from the search results, call this script using the retrieve command to get the full guide. You can pass multiple IDs separated by commas.
npx -y modern-web-guidance@latest retrieve "<id>"
Example Output:
The markdown content of the guide describing implementation steps...
Using npx
- IMPORTANT: on Windows, using
npxmay fail. Usenpx.cmd ...instead. - Network access is required for fetching npm packages needed by the task.
- If the
npx -y modern-web-guidance…command hangs, you may be offline. Try running again in offline mode:npx --offline …. - The
--skill-versionflag is used to determine if this SKILL.md is out of date. If it is, a warning message is logged to stderr.
What ships with it
60 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.
- guides/accessibility/accessibility.md 24 KB
- guides/accessibility/accessible-error-announcement.md 6.9 KB
- guides/built-in-ai/language-detection.md 3.5 KB
- guides/built-in-ai/language-model.md 7.1 KB
- guides/built-in-ai/summarizer.md 5.9 KB
- guides/built-in-ai/translator.md 5.3 KB
- guides/css-layout/css-layout.md 20 KB
- guides/css/css.md 27 KB
- guides/css/highlight-text-ranges.md 5.4 KB
- guides/forms/animated-select-picker.md 7.8 KB
- guides/forms/autofill-address-form.md 4.1 KB
- guides/forms/autofill-highlight-inputs.md 2.3 KB
- guides/forms/autofill-payment-form.md 8.5 KB
- guides/forms/autofill-sign-in-form.md 9.9 KB
- guides/forms/autofill-sign-up-form.md 11 KB
- guides/forms/brand-consistent-forms.md 8.3 KB
- guides/forms/branded-select-styling.md 5.5 KB
- guides/forms/custom-select-picker-layouts.md 5.0 KB
- guides/forms/form-fields-automatically-fit-contents.md 5.8 KB
- guides/forms/forms.md 14 KB
- guides/forms/required-field-feedback.md 6.8 KB
- guides/forms/rich-media-picker.md 6.6 KB
- guides/forms/select-menu-interaction.md 5.6 KB
- guides/forms/validate-input-after-interaction.md 8.6 KB
- guides/html/html.md 18 KB
- guides/passkeys/passkey-authentication.md 9.7 KB
- guides/passkeys/passkey-conditional-create.md 6.5 KB
- guides/passkeys/passkey-management.md 9.3 KB
- guides/passkeys/passkey-reauthentication.md 4.9 KB
- guides/passkeys/passkey-registration.md 9.3 KB
- guides/passkeys/passkeys.md 4.2 KB
- guides/performance/batch-analytics-events.md 6.4 KB
- guides/performance/break-up-long-tasks.md 2.1 KB
- guides/performance/calculate-total-foreground-time.md 2.9 KB
- guides/performance/conditional-async-dependencies.md 3.6 KB
- guides/performance/defer-rendering-heavy-content.md 6.3 KB
- guides/performance/defer-work-until-scroll-ends.md 3.3 KB
- guides/performance/deprioritize-background-fetches.md 1.8 KB
- guides/performance/detect-initial-visibility-state.md 4.5 KB
- guides/performance/efficient-background-processing.md 5.0 KB
- guides/performance/faster-spa-view-transitions.md 3.4 KB
- guides/performance/full-session-analytics.md 5.7 KB
- guides/performance/identify-heavy-scripts.md 4.2 KB
- guides/performance/identify-inp-causes.md 5.4 KB
- guides/performance/improve-next-page-load-performance.md 7.1 KB
- guides/performance/interactions-in-complex-layouts.md 3.4 KB
- guides/performance/optimize-image-priority.md 4.0 KB
- guides/performance/optimize-preload-priority.md 3.3 KB
- guides/performance/optimize-script-priority.md 2.6 KB
- guides/performance/performance.md 18 KB
- guides/performance/resolution-optimized-pseudo-elements.md 2.3 KB
- guides/performance/schedule-tasks-by-priority.md 2.2 KB
- guides/performance/sequence-distributed-events.md 3.5 KB
- guides/privacy/privacy.md 11 KB
- guides/security/security.md 25 KB
- guides/user-experience/adapt-scrollbar-to-contrast-preferences.md 3.5 KB
- guides/user-experience/anchor-positioning-tab-underline.md 2.9 KB
- guides/user-experience/animate-element-entry-exit.md 5.0 KB
- guides/user-experience/animate-to-from-top-layer.md 5.5 KB
- guides/user-experience/animate-to-intrinsic-sizes.md 5.3 KB
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.
- 4d ago First seen · 115 lines · 233 tokens per session scan A a1ed8448959e
modern-web-guidance is a skill published in the GitHub repository modernweb-dev/rocket (394 stars, last pushed yesterday), licensed MIT. It adds 233 tokens to every session and 1,291 once invoked, about $0.0012 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to modern-web-guidance, differing in 16 lines, and is treated as a copy.
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