Caption Writer
A caption is not a description of the post. It's the part of the post that does the work —
it stops the scroll, earns attention, and drives one action. Done well it carries the
post; done generically it sinks even great visuals under emoji and hashtag noise.
Two principles run through everything here:
- The first line is the whole game. On every platform the caption is truncated — the
reader sees one line and a "…more." If that line doesn't earn the tap, the rest is never
read. Write the first line like its only job is to win the second line.
- Every caption serves one goal. Awareness, comments, saves, clicks, community, or
conversion — the goal dictates the structure and the call to action. A caption "to get
engagement" is a caption with no goal.
Step 0 — Read the foundation first (required)
Load brand-profile.md and voice.md before writing a word. The voice fingerprint, the
"never" list, and the brand guardrails are non-negotiable. A caption that doesn't sound like
them is a failure even if it's clever. If neither exists, run brand-profile (and
voice-builder if samples exist) first.
Step 1 — Establish four inputs
Don't write until you know these. Infer what you can; ask only what you can't:
- Platform — the mechanics are different on each (see
references/platforms.md).
- The asset — what's in the photo/video/carousel? The caption complements the visual; it
shouldn't narrate what the eye already sees.
- The goal — awareness, comments, saves, clicks/traffic, community, or conversion.
- The topic / point — what this specific post is about, and the one idea it lands.
If the user gives you only "write a caption for this," ask at most one or two questions
(usually platform + goal) and proceed.
Step 2 — Choose the format, then the goal-driven structure
Pick the caption format that fits the asset and point — story, value/how-to, hot take,
question, behind-the-scenes, social proof, announcement, relatable (see
references/formats.md). Then shape it with the goal-driven structure and CTA from
references/frameworks.md. Format gives it a recognizable shape; goal gives it a job.
Step 3 — Write the first line first
Spend disproportionate effort here. Draft 3–5 candidate opening lines and pick the one that
most makes a stranger need the next line — within the platform's preview cutoff. Never waste
the first line on a greeting, a hashtag, "Happy Monday!", or a restatement of the image. See
references/first-line.md.
Step 4 — Build the body and one CTA
- Body: deliver the value or story the first line promised, in the brand's voice, at the
right length for the platform and goal (short isn't always better — match it). Use line
breaks and whitespace where the platform rewards scannability.
- CTA: exactly one, matched to the goal ("save this for your next launch," "what would you
add?", "link in bio"). Two CTAs split the action and kill both. Respect any "never hard-sell
here" guardrails from the brand profile.
Step 5 — Mechanics: hashtags, links, formatting
Apply the platform's current norms from references/platforms.md: how many hashtags (and
whether to use any), where links go and whether they hurt reach, line-break rendering, and the
ideal length. Getting mechanics wrong makes a good caption underperform.
Step 6 — Deliver options, recommend one
Give the user 2–3 distinct caption options (genuinely different angles or formats, not the
same caption reworded), then recommend one with a one-line rationale tied to the goal. People
choose faster from real alternatives than from a single take.
Quality bar — self-check before delivering
- Does the first line stop the scroll on its own, inside the preview cutoff?
- Does it sound like them — fingerprint hit, "never" list respected, banned words absent?
- Is there one clear CTA matched to the goal?
- Does the caption complement the asset rather than describe it?
- Are hashtags/links/length correct for the platform?
- Would a real person stop, read, and act — or scroll past?
If the first line is weak, rewrite it before anything else. It's 80% of the result.
Edge cases
- No asset described: ask what's in it, or write a caption that works for the stated topic
and flag that the first line may need tuning to the visual.
- Multiple platforms requested: don't paste the same caption everywhere. Adapt the hook,
length, hashtags, and CTA to each platform's mechanics (see
cross-platform-repurposing for
doing this at scale).
- Regulated/sensitive brand: apply the brand profile's compliance guardrails — no
forbidden claims, required disclaimers, careful CTAs.
- Carousel / multi-image: the caption supports the swipe — the first line should pull
people into slide 1; consider a "keep reading / swipe" nudge only if it fits the voice.
- Link-driven goal on a no-link platform (e.g., Instagram feed): route to "link in bio"
and say so; don't write a clickable-link CTA where links aren't clickable.
- Very short-form platforms (X, Threads, Bluesky): the caption is the whole post — lead
with the point, cut everything else.
Related skills
brand-profile, voice-builder — read first; supply voice and guardrails.
hook-writer — for deeper work on the opening hook.
linkedin-post-writer, thread-writer — specialized long-form / thread copy.
hashtag-strategy — for a fuller hashtag system.
cross-platform-repurposing — adapt one caption across many platforms.
scheduling-and-queue — push the finished caption to WoopSocial to schedule.
References
references/platforms.md — per-platform caption mechanics (limits, fold, hashtags, links).
references/frameworks.md — caption structure, goal→structure mapping, length, CTA library.
references/formats.md — caption formats/archetypes and when to use each.
references/first-line.md — opening-line craft; winning the "…more" tap.
references/examples.md — worked captions across platforms and goals.
1---
2name: caption-writer
3description: >-
4 Use to write platform-native social media captions (post copy) in the brand's voice — the
5 words that accompany a post on Instagram, LinkedIn, TikTok, Facebook, X/Twitter, Threads,
6 Pinterest, YouTube, or Bluesky. Run when the user says "write a caption," "caption this,"
7 "post copy," "write the copy for this photo/video/Reel," "IG caption," "what should I write
8 for this post," or needs the words to go with a visual. Reads brand-profile and voice first
9 so captions sound like the brand, not generic AI. For long-form LinkedIn thought-leadership
10 posts use linkedin-post-writer; for X/Threads multi-post threads use thread-writer; for video
11 scripts use the video skills. This skill writes the caption itself.
12metadata:
13 version: 1.0.0
14license: MIT
15---
16
17# Caption Writer
18
19A caption is not a description of the post. It's the part of the post that does the *work* —
20it stops the scroll, earns attention, and drives one action. Done well it carries the
21post; done generically it sinks even great visuals under emoji and hashtag noise.
22
23Two principles run through everything here:
24
251. **The first line is the whole game.** On every platform the caption is truncated — the
26 reader sees one line and a "…more." If that line doesn't earn the tap, the rest is never
27 read. Write the first line like its only job is to win the second line.
282. **Every caption serves one goal.** Awareness, comments, saves, clicks, community, or
29 conversion — the goal dictates the structure and the call to action. A caption "to get
30 engagement" is a caption with no goal.
31
32## Step 0 — Read the foundation first (required)
33
34Load `brand-profile.md` and `voice.md` before writing a word. The voice fingerprint, the
35"never" list, and the brand guardrails are non-negotiable. A caption that doesn't sound like
36them is a failure even if it's clever. If neither exists, run `brand-profile` (and
37`voice-builder` if samples exist) first.
38
39## Step 1 — Establish four inputs
40
41Don't write until you know these. Infer what you can; ask only what you can't:
42
43- **Platform** — the mechanics are different on each (see `references/platforms.md`).
44- **The asset** — what's in the photo/video/carousel? The caption complements the visual; it
45 shouldn't narrate what the eye already sees.
46- **The goal** — awareness, comments, saves, clicks/traffic, community, or conversion.
47- **The topic / point** — what this specific post is about, and the one idea it lands.
48
49If the user gives you only "write a caption for this," ask at most one or two questions
50(usually platform + goal) and proceed.
51
52## Step 2 — Choose the format, then the goal-driven structure
53
54Pick the caption **format** that fits the asset and point — story, value/how-to, hot take,
55question, behind-the-scenes, social proof, announcement, relatable (see
56`references/formats.md`). Then shape it with the **goal-driven structure** and CTA from
57`references/frameworks.md`. Format gives it a recognizable shape; goal gives it a job.
58
59## Step 3 — Write the first line first
60
61Spend disproportionate effort here. Draft 3–5 candidate opening lines and pick the one that
62most makes a stranger need the next line — within the platform's preview cutoff. Never waste
63the first line on a greeting, a hashtag, "Happy Monday!", or a restatement of the image. See
64`references/first-line.md`.
65
66## Step 4 — Build the body and one CTA
67
68- **Body:** deliver the value or story the first line promised, in the brand's voice, at the
69 right length for the platform and goal (short isn't always better — match it). Use line
70 breaks and whitespace where the platform rewards scannability.
71- **CTA:** exactly one, matched to the goal ("save this for your next launch," "what would you
72 add?", "link in bio"). Two CTAs split the action and kill both. Respect any "never hard-sell
73 here" guardrails from the brand profile.
74
75## Step 5 — Mechanics: hashtags, links, formatting
76
77Apply the platform's current norms from `references/platforms.md`: how many hashtags (and
78whether to use any), where links go and whether they hurt reach, line-break rendering, and the
79ideal length. Getting mechanics wrong makes a good caption underperform.
80
81## Step 6 — Deliver options, recommend one
82
83Give the user **2–3 distinct caption options** (genuinely different angles or formats, not the
84same caption reworded), then recommend one with a one-line rationale tied to the goal. People
85choose faster from real alternatives than from a single take.
86
87## Quality bar — self-check before delivering
88
89- Does the **first line** stop the scroll on its own, inside the preview cutoff?
90- Does it **sound like them** — fingerprint hit, "never" list respected, banned words absent?
91- Is there **one** clear CTA matched to the goal?
92- Does the caption **complement** the asset rather than describe it?
93- Are hashtags/links/length **correct for the platform**?
94- Would a real person stop, read, and act — or scroll past?
95
96If the first line is weak, rewrite it before anything else. It's 80% of the result.
97
98## Edge cases
99
100- **No asset described:** ask what's in it, or write a caption that works for the stated topic
101 and flag that the first line may need tuning to the visual.
102- **Multiple platforms requested:** don't paste the same caption everywhere. Adapt the hook,
103 length, hashtags, and CTA to each platform's mechanics (see `cross-platform-repurposing` for
104 doing this at scale).
105- **Regulated/sensitive brand:** apply the brand profile's compliance guardrails — no
106 forbidden claims, required disclaimers, careful CTAs.
107- **Carousel / multi-image:** the caption supports the swipe — the first line should pull
108 people *into* slide 1; consider a "keep reading / swipe" nudge only if it fits the voice.
109- **Link-driven goal on a no-link platform** (e.g., Instagram feed): route to "link in bio"
110 and say so; don't write a clickable-link CTA where links aren't clickable.
111- **Very short-form platforms** (X, Threads, Bluesky): the caption *is* the whole post — lead
112 with the point, cut everything else.
113
114## Related skills
115
116- `brand-profile`, `voice-builder` — read first; supply voice and guardrails.
117- `hook-writer` — for deeper work on the opening hook.
118- `linkedin-post-writer`, `thread-writer` — specialized long-form / thread copy.
119- `hashtag-strategy` — for a fuller hashtag system.
120- `cross-platform-repurposing` — adapt one caption across many platforms.
121- `scheduling-and-queue` — push the finished caption to WoopSocial to schedule.
122
123## References
124
125- `references/platforms.md` — per-platform caption mechanics (limits, fold, hashtags, links).
126- `references/frameworks.md` — caption structure, goal→structure mapping, length, CTA library.
127- `references/formats.md` — caption formats/archetypes and when to use each.
128- `references/first-line.md` — opening-line craft; winning the "…more" tap.
129- `references/examples.md` — worked captions across platforms and goals.