CtrlK
BlogDocsLog inGet started
Tessl Logo

modern-format

Use when reviewing image assets, markup, and CDN or build transforms related to Use modern image formats (WebP, AVIF). Check encoded size, rendered size, loading strategy, and above-the-fold impact together.

65

Quality

78%

Does it follow best practices?

Run evals on this skill

Adds up to 20 points to the overall score

View guide

SecuritybySnyk

Passed

No findings from the security scan

Fix and improve this skill with Tessl

tessl review fix ./skills/modern-format/SKILL.md
SKILL.md
Quality
Evals
Security

Quality

Content

72%

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

A well-structured, actionable skill body with good progressive disclosure, held back by some redundant explanation of known facts and the absence of an explicit verification checkpoint in the workflow.

Suggestions

Trim the introductory motivation paragraph and the 'Explain' compression/browser-support facts that Claude already knows, or move them into references/rule.md.

Add an explicit validation step to the Fix workflow, e.g. 'Confirm in DevTools that the <picture> serves AVIF/WebP and the <img> fallback still loads'.

Relocate version-specific support data ('as of 2024', 'Chrome 85+, Firefox 93+, Safari 16.4+') to a reference or a clearly marked section so time-sensitive content does not inflate the body.

DimensionReasoningScore

Conciseness

The body is mostly efficient and well-structured, but the opening motivation paragraph and the 'Explain' section restate compression facts Claude already knows, and inline time-sensitive versions ('as of 2024', 'Safari 16.4+') are not isolated in a deprecated section.

2 / 3

Actionability

The Check and Fix sections give concrete, executable guidance with named tools (Squoosh/Sharp), specific quality values (80%/60%), and copy-paste markup patterns such as '<source type="image/avif">' and an '@supports (background-image: url(".webp"))' query.

3 / 3

Workflow Clarity

Check and Fix are clearly numbered and sequenced, but there is no explicit validation checkpoint (e.g., verify the <picture> fallback renders or confirm WebP is served in DevTools) within the workflow, so checkpoints are implicit.

2 / 3

Progressive Disclosure

The body is a well-organized overview split into labeled sections that points to a real, one-level-deep 'references/rule.md' for full implementation details, matching the clear-overview-with-signaled-reference anchor.

3 / 3

Total

10

/

12

Passed

Description

85%

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 strong, specific description with an explicit trigger and a clear niche, weakened only by trigger-term phrasing that is more technical than the natural language users would actually say.

Suggestions

Add natural user phrasings to the trigger such as 'optimize images', 'convert images to WebP/AVIF', and 'compress JPEG/PNG' alongside the existing technical terms.

Soften the awkward 'related to Use modern image formats (WebP, AVIF)' phrasing so the trigger reads more like a user request.

DimensionReasoningScore

Specificity

The description lists multiple 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' — matching the anchor for multiple specific concrete actions.

3 / 3

Completeness

It clearly answers what the skill does (review/check image assets, markup, CDN transforms and size/loading metrics) and when to use it via an explicit 'Use when reviewing...' trigger clause.

3 / 3

Trigger Term Quality

It includes relevant terms (WebP, AVIF, CDN, above-the-fold, image assets) but leans technical and omits common user phrasings like 'optimize images', 'convert to WebP', 'compress', or the legacy JPEG/PNG names, so common variations are missing.

2 / 3

Distinctiveness Conflict Risk

The WebP/AVIF modern-format niche with delivery-specific triggers (CDN/build transforms, above-the-fold impact) is distinct and unlikely to fire for unrelated skills.

3 / 3

Total

11

/

12

Passed

Validation

93%

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

Validation15 / 16 Passed

Validation for skill structure

CriteriaDescriptionResult

metadata_version

'metadata.version' is missing

Warning

Total

15

/

16

Passed

Repository
thedaviddias/Front-End-Checklist
Reviewed

Table of Contents

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.