YouTube Description Writer

The description does three jobs: it hooks the reader in its first 150 characters, it feeds YouTube and Google search, and it organizes the video with chapters and links. This skill writes all three layers.

When to use

• User says "write the description for this video"
• User has a video and wants chapters, keywords, and links structured
• User wants the first 150 chars optimized for the search/suggested snippet
• User is about to upload and needs the content that ships with the video

The three layers of a description

Layer	Chars	Job
Hook	first ~150	the only text visible before "Show more"; also the search/suggested snippet. Lead with the payoff or the question and the search phrase.
Body	~150 to 1,000	expand the value, restate the promise, place the main keywords naturally, link the key resource.
Furniture	rest, up to 5,000	chapters, links, social, credits, hashtags. Skimmable, labeled.

Steps

Voice profile first (all drafts). If ../../references/voice-profile.md has filled: yes, load it and match the user's voice fingerprint, hard rules, and CTA/link style throughout. If it is not filled, mention once that yt-community-post-writer --mode profile can learn their voice from a few posts, then proceed with the generic voice rules.

Never invent the specifics. The rules below ask for a concrete number, a date and a named entity, because that is what separates a real post from a generated one. Take them from what the user actually said in this conversation. Do not invent a figure, a date, a client name or a result, and do not soften a vague claim into a plausible-looking number. If the user has nothing concrete for a beat, ask them once, and if they still have nothing, drop the claim rather than decorate it. A published invented number is a retraction; a missing one is only a weaker post.

1. Gather inputs. The title (so the description complements it), the video's payoff, the main search phrase plus 3 to 5 secondary keywords, the chapter beats with timestamps, any links (lead magnet, gear, socials), and whether it is long-form or a Short. If a URL is given, parse it with lib/url_parser.py.
2. Write the first 150 chars as a second hook. Lead with the payoff or the question, work the primary keyword in naturally, and make it read well as a standalone snippet. This is not "welcome back to the channel".
3. Write the body. 2 to 4 short paragraphs that restate the promise and place the keywords without stuffing. Put the single most important link here.
4. Add chapters. Timestamps starting at 0:00, each label short and descriptive. YouTube needs at least 3 chapters and a 0:00 start to enable the chapter UI. For a Short, skip chapters.
5. Add the furniture. Links section, socials, a one-line CTA (subscribe for the specific reason, not "smash like"), and 3 to 5 relevant hashtags at the very end (the first 3 surface above the title).
6. Humanizer pass and length check. Scrub 2026 AI vocabulary by paragraph density (one marker is fine; three in one paragraph means rewrite it), cap em dashes at about one per 100 words (replace the excess with a comma, colon or line break, never a period), strip reveal bridges and sincerity openers ("let me be honest"); never add a hedge or confession the creator did not write. Keep the whole thing under 5,000 chars. Confirm the first 150 read well truncated.
7. Approval card. Show the description with a marked 150-char cutoff and the total char count.
8. On approval. This description is the content passed to lib.publish(kind="video"|"short", draft_text=<description>, title=<title>, ...). The title travels separately in platformSettings.youtube.title.

Hard rules

Global voice rules: see root SKILL.md Voice rules. Additional skill-specific rules:

• 5,000-char hard cap. The first 150 chars carry the hook and the search phrase.
• The first line is never boilerplate ("Hi everyone, welcome back").
• Chapters: at least 3, first one at 0:00, short labels. Long-form only.
• Keywords appear in natural sentences, never as a comma-separated dump.
• Hashtags: 3 to 5 max, at the end. More than 15 makes YouTube ignore all of them.
• Every link is labeled so the reader knows what it is before clicking.

Anti-patterns (skill will refuse)

• A boilerplate greeting in the first 150 chars.
• A keyword dump or a tag wall pretending to be a description.
• 15+ hashtags (YouTube strips them all).
• Em dashes above the cap (more than about one per 100 words), or an em dash swapped for a period.
• "Smash that like button and subscribe" dead phrasing.
• Chapters that do not start at 0:00 (the UI will not render them).
• Raw unlabeled links.

Resources

• ../../references/algorithm-heuristics.md - the 150-char snippet, chapters, search signals
• ../../references/voice-rules.md - the canonical voice rules
• references/description-template.md - the full skeleton with chapters, links, hashtags

Related skills

• yt-title-optimizer - the title the description complements
• yt-hook-scripter - the spoken first 30 seconds (different from the written hook)
• yt-content-planner - keyword and link strategy across a series