youtube-downloader
Download YouTube videos and HLS streams (m3u8) from platforms like Mux, Vimeo, etc. using yt-dlp and ffmpeg. Use this skill when users request downloading videos, extracting audio, handling protected streams with authentication headers, or troubleshooting download issues like nsig extraction failures, 403 errors, or cookie extraction problems.
Install with Tessl CLI
npx tessl i github:fernandezbaptiste/claude-code-skills --skill youtube-downloader90
Does it follow best practices?
If you maintain this skill, you can automatically optimize it using the tessl CLI to improve its score:
npx tessl skill review --optimize ./path/to/skillValidation for skill structure
Discovery
100%Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.
This is an excellent skill description that hits all the marks. It provides specific capabilities, uses natural trigger terms that users would actually say, explicitly states when to use the skill, and carves out a distinct niche with platform and tool-specific terminology. The inclusion of common error types (nsig extraction, 403 errors, cookie problems) is particularly valuable for matching troubleshooting requests.
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | Lists multiple specific concrete actions: 'Download YouTube videos', 'HLS streams (m3u8)', 'extracting audio', 'handling protected streams with authentication headers', 'troubleshooting download issues'. Also names specific tools (yt-dlp, ffmpeg) and platforms (Mux, Vimeo). | 3 / 3 |
Completeness | Clearly answers both what (download videos, extract audio, handle protected streams, troubleshoot issues) AND when with explicit 'Use this skill when...' clause listing specific trigger scenarios including error types. | 3 / 3 |
Trigger Term Quality | Excellent coverage of natural terms users would say: 'YouTube videos', 'HLS streams', 'm3u8', 'Mux', 'Vimeo', 'yt-dlp', 'ffmpeg', 'downloading videos', 'extracting audio', 'nsig extraction failures', '403 errors', 'cookie extraction'. These are terms users would naturally use when seeking help. | 3 / 3 |
Distinctiveness Conflict Risk | Highly distinctive with clear niche: video downloading specifically via yt-dlp/ffmpeg, with platform-specific mentions (YouTube, Mux, Vimeo) and technical error types (nsig, 403, cookies). Unlikely to conflict with general media or file handling skills. | 3 / 3 |
Total | 12 / 12 Passed |
Implementation
77%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
This is a comprehensive and highly actionable skill with excellent workflow clarity and executable examples. The main weakness is verbosity - the document tries to cover many scenarios inline rather than splitting advanced topics into separate reference files. The troubleshooting sections and HLS content could be moved to separate files to improve token efficiency.
Suggestions
Move the HLS Stream Downloads section to a separate reference file (e.g., references/hls-downloads.md) and link to it from the main skill
Consolidate the 'Non-Technical User Experience' section - the response template and choice offerings are verbose and could be condensed
Move detailed troubleshooting to a separate references/troubleshooting.md file, keeping only a brief quick-reference in the main skill
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The skill contains useful information but is verbose in places, with some redundancy between sections (e.g., troubleshooting steps repeated in multiple places, extensive explanation of user-facing templates). The 'Non-Technical User Experience' section could be more concise. | 2 / 3 |
Actionability | Provides fully executable commands throughout with specific examples for yt-dlp, ffmpeg, and the bundled script. Commands are copy-paste ready with clear parameter explanations and expected outputs. | 3 / 3 |
Workflow Clarity | Clear multi-step workflows with explicit validation checkpoints (e.g., 'Verify Download Quality' step, format checking before download). The Agent Execution Checklist and Reliable Download SOP provide clear sequences with error recovery paths and retry logic. | 3 / 3 |
Progressive Disclosure | References external files appropriately (references/po-token-setup.md) but the main document is quite long with some content that could be split out (HLS section, troubleshooting). The structure is good but the document itself is monolithic. | 2 / 3 |
Total | 10 / 12 Passed |
Validation
100%Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.
Validation — 11 / 11 Passed
Validation for skill structure
No warnings or errors.
- 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.