Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/samber/cc-skills/substack-ghostwritingnpx skills add samber/cc-skills --skill substack-ghostwritinggit clone --depth 1 https://github.com/samber/cc-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/samber/cc-skills/substack-ghostwriting)<a href="https://agentmods.dev/skills/samber/cc-skills/substack-ghostwriting"><img src="https://agentmods.dev/badge/skills/samber/cc-skills/substack-ghostwriting.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00207 | $0.03463 |
| Opus 5 | $0.00103 | $0.01732 |
| Sonnet 5 | $0.00041 | $0.00693 |
| Haiku 4.5 | $0.00021 | $0.00346 |
Grade A, and why
substack-ghostwriting scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
Copies of this mod
1 near-identical copy found in the catalogue:
- substack-ghostwriting — 97% identical, 2 lines differ
How it starts
The opening of the file, as written. The whole thing — 244 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Substack Ghostwriting & Content Optimization
A skill for writing Substack content — both newsletter issues (email-first) and web posts (web-first articles/essays) — that grows subscribers and converts readers. Handles two voice modes (own voice, ghostwriting) and two format modes (newsletter issue, web post).
Core philosophy
Substack is not a blog with an email list. It's a social-media-newsletter hybrid with an algorithm that optimizes for subscriptions, not engagement. This changes everything about how you write, format, and distribute content on the platform.
The algorithm's incentives genuinely align with quality. Substack's revenue comes from subscription cuts (not ads), so gaming engagement metrics doesn't help. What helps: writing content good enough that readers convert to paid subscribers and recommend you to others.
For ghostwriting specifically: the job is capturing someone's existing insights in their voice, not generating insights from scratch. As Nicolas Cole frames it: clients are "insights-rich and time-poor", writers are "time-rich but insights-poor." The art is extraction and voice matching.
Platform formatting constraints
Substack is a social-media-newsletter hybrid with an algorithm that optimizes for subscriptions, not engagement. Revenue comes from subscription cuts (not ads), so quality genuinely wins. For ghostwriting: the job is capturing someone's existing insights in their voice — clients are "insights-rich and time-poor."
Read references/platform-constraints.md for post fields, Notes limits, special content blocks, and media embeds.
Mode detection
Determine two dimensions:
Voice dimension:
- Own voice — the user writes/publishes under their own name. Go directly to the Writing Workflow.
- Ghostwriting — writing in someone else's voice, or preparing content for a client. Complete the Ghostwriting Workflow first, then the Writing Workflow.
Format dimension:
- Newsletter issue (email-first) — sent to subscribers' inboxes. Subject line and email formatting matter most. Read
references/email-formatting.mdduring Phase 3. - Web post (web-first) — published as a Substack article/essay, discoverable via search and Substack's feed. SEO and web formatting matter most. Read
references/web-post-formatting.mdduring Phase 3.
What ships with it
7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 3d ago First seen · 244 lines · 207 tokens per session scan A c16437af0b8f
substack-ghostwriting is a skill published in the GitHub repository samber/cc-skills (198 stars, last pushed 3d ago), licensed MIT. It adds 207 tokens to every session and 3,463 once invoked, about $0.0010 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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