Modern Web Guidance is a source repository for coding-agent skills that provide web-platform guidance, recommended practices, and browser compatibility information. It helps coding agents choose newer web APIs and patterns when generating web applications. The catalogue skills are the guidance produced and maintained by this project.
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 GoogleChrome/modern-web-guidance-src --skill modern-web-guidancegit clone --depth 1 https://github.com/GoogleChrome/modern-web-guidance-srcWrote 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/googlechrome/modern-web-guidance-src/modern-web-guidance)<a href="https://agentmods.dev/skills/googlechrome/modern-web-guidance-src/modern-web-guidance"><img src="https://agentmods.dev/badge/skills/googlechrome/modern-web-guidance-src/modern-web-guidance/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/googlechrome/modern-web-guidance-src/modern-web-guidance"><img src="https://agentmods.dev/badge/skills/googlechrome/modern-web-guidance-src/modern-web-guidance.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 5 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium MCP Rug Pull · line 38 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 65 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 75 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 94 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 94 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
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 | $0.00233 | $0.01525 |
| Opus 5 | $0.00117 | $0.00763 |
| Sonnet 5 | $0.00047 | $0.00305 |
| Haiku 4.5 | $0.00023 | $0.00153 |
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 5d 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 — 124 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 SKILL_VERSION
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>"
If the output is truncated, you must repeat the command but redirect to a file and read that file.
Example Output:
The markdown content of the guide describing implementation steps...
Step 3. Verify Guidance Compliance
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.
- 5d ago Changed · -1 lines 2286c7bac00d
- 6d ago Changed · +4 lines ee692ab7b25d
- 10d ago First seen · 121 lines · 233 tokens per session scan A f48f3b223592
modern-web-guidance is a skill published in the GitHub repository GoogleChrome/modern-web-guidance-src (1,022 stars, last pushed today), licensed Apache-2.0. It adds 233 tokens to every session and 1,525 once invoked, about $0.0012 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 2026-08-30.
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