progressive-jpeg

Use when reviewing image assets, markup, and CDN or build transforms related to Use progressive JPEG encoding. Check encoded size, rendered size, loading strategy, and above-the-fold impact together.

Quality

62%

Does it follow best practices?

Run evals on this skill

Adds up to 20 points to the overall score

View guide

Securityby

Passed

No findings from the security scan

Fix and improve this skill with Tessl

tessl review fix ./skills/progressive-jpeg/SKILL.md

Quality

Content

50%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

The skill is well-structured for progressive disclosure — a lean overview correctly deferring all code and framework specifics to a real, one-level-deep reference file. However, the inline guidance is vague where it matters: the Check and Fix sections name the action but give no command or method, and the same perceived-performance explanation is repeated across three sections instead of being stated once.

Suggestions

Put one executable check inline in the Check section (e.g., `identify -verbose image.jpg | grep Interlace` or `file image.jpg`) and one conversion command in the Fix section (e.g., `convert input.jpg -interlace JPEG output.jpg`), leaving framework-specific variants in references/rule.md.

Collapse the intro paragraph, Quick Reference bullets, and Explain section into a single statement of what progressive JPEGs are and why they help — the same blurry-preview/perceived-performance fact is currently stated three times.

Make the workflow explicit: number the steps (1. Check format → 2. Convert offenders → 3. Verify in DevTools with throttling) so the DevTools verification becomes a real checkpoint rather than a passing mention in the Code Review section.

Dimension	Reasoning	Score
Conciseness	The body restates the same fact three times ('Progressive JPEGs display a low-quality preview immediately rather than loading line-by-line', 'show blurry preview immediately, then sharpen', 'Explain how progressive JPEGs show a low-quality preview') and explains a concept Claude already knows. It is short overall, but the intro paragraph, Quick Reference, and Explain sections are redundant and could be collapsed into one.	3 / 5
Actionability	'Check if JPEG images are saved in progressive format' and 'Convert baseline JPEGs to progressive format' are directives with no method, command, or tool — the executable details (identify -verbose, convert -interlace JPEG, sharp) all live in references/rule.md. Only the Code Review section approaches concrete guidance ('Flag exact files or components... and describe how to confirm the fix in DevTools').	2 / 5
Workflow Clarity	The Check → Fix → Explain → Code Review section order implies a rough sequence, and verification is mentioned ('describe how to confirm the fix in DevTools'), but no step is numbered or defined and the verification checkpoint is implicit rather than an explicit validate-then-proceed step.	3 / 5
Progressive Disclosure	The body is a ~40-line overview with clean sections and a single, clearly signaled, one-level-deep pointer ('For full implementation details, code examples, and framework-specific guidance, see references/rule.md') to a real file that holds all the code and framework guidance, with no further nesting. This is an appropriately split overview/navigation structure.	5 / 5
	Total	13 / 20 Passed

Description

75%Weight 40%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A solid description with an explicit 'Use when' trigger, a named niche, and several concrete checks; all four dimensions sit just below top because coverage is not comprehensive and the rule title is embedded verbatim ('related to Use progressive JPEG encoding'), which reads awkwardly and blurs both the what and the when.

Dimension	Reasoning	Score
Specificity	The description lists several concrete actions — 'reviewing image assets, markup, and CDN or build transforms' and 'Check encoded size, rendered size, loading strategy, and above-the-fold impact together' — with only minor gaps (it never mentions converting baseline JPEGs or verifying the fix, which the skill body covers). Not comprehensive enough for the 5 anchor.	4 / 5
Completeness	Both parts are present: an explicit 'Use when reviewing image assets, markup, and CDN or build transforms' trigger and a concrete what ('Check encoded size, rendered size, loading strategy, and above-the-fold impact together'). It is not a 5 because the core action is left implicit — the description never says the skill flags or converts non-progressive JPEGs — and the awkwardly embedded rule title ('related to Use progressive JPEG encoding') muddies the trigger phrasing.	4 / 5
Trigger Term Quality	Good natural-term coverage: 'progressive JPEG encoding', 'image assets', 'markup', 'CDN or build transforms', 'above-the-fold' are all phrases a user would plausibly say. A few common variations are missing (e.g., '.jpg'/'.jpeg' extensions, 'image optimization', 'perceived performance', 'LCP'), so it falls short of the comprehensive synonym coverage of the 5 anchor.	4 / 5
Distinctiveness Conflict Risk	'Progressive JPEG encoding' carves out a clear niche with distinct triggers, but the broad review framing ('image assets, markup, and CDN or build transforms', 'loading strategy') risks overlap with closely related image-delivery skills such as lazy-loading, responsive-image, or WebP/AVIF rules — minor overlap risk, matching the 4 anchor rather than the minimal-conflict 5.	4 / 5
	Total	16 / 20 Passed

Validation

93%

Warnings & errors only

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 15 / 16 Passed

Validation for skill structure

Criteria	Description	Result
metadata_version	'metadata.version' is missing	Warning

	Total	15 / 16 Passed

Repository: thedaviddias/Front-End-Checklist
Path: skills/progressive-jpeg/SKILL.md
Commit: 7bfd868

Reviewed: 1 day ago

Table of Contents

Discovery Implementation Validation

Is this your skill?

If you maintain this skill, you can claim it as your own. Once claimed, you can manage eval scenarios, bundle related skills, attach documentation or rules, and ensure cross-agent compatibility.