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 skills add ericrisco/rsc-harness --skill newslettergit clone --depth 1 https://github.com/ericrisco/rsc-harnessWrote 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/ericrisco/rsc-harness/newsletter)<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/newsletter"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/newsletter/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/newsletter"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/newsletter.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 5.1 | $0.00080 | $0.02762 |
| Opus 5 | $0.00040 | $0.01381 |
| Sonnet 5 | $0.00016 | $0.00552 |
| Haiku 4.5 | $0.00008 | $0.00276 |
Grade A, and why
newsletter 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 7d 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.
How it starts
The opening of the file, as written. The whole thing — 153 lines — stays where its author put it; the contents beside it link to each section on GitHub.
newsletter
Run the newsletter as a product you ship on a cadence, not a one-off send. The job is the system around the recurring issue: the subject + preview that earns the open, the issue body that earns the click, the welcome sequence that activates a new subscriber, the cadence and segmentation that keep the list healthy, the growth loops that compound it, and a scorecard that still tells the truth after Apple broke open rates. Every send is one episode of an ongoing show — design the show, not the episode.
When NOT to use — route instead
| The ask | Route to |
|---|---|
| One-off product launch announcement or campaign drip nurture | ../marketing/SKILL.md |
| Mail lands in spam; set up SPF / DKIM / DMARC, tracking domain, reputation | ../email-deliverability/SKILL.md |
| Write the subscribe / opt-in landing page copy | ../landing-copy/SKILL.md |
| Define the house voice, tone, and vocabulary the newsletter speaks in | ../brand-voice/SKILL.md |
| Win back / reactivate lapsed paying customers (lifecycle, not readers) | ../retention/SKILL.md |
| Produce the underlying long-form articles the issue links out to | ../content-engine/SKILL.md |
| Sample size / significance / MDE math for the test itself | ../ab-testing/SKILL.md |
| Source or scrape new contacts; prospect an un-opted-in list | ../lead-gen/SKILL.md, ../cold-outreach/SKILL.md |
| Actually wire the send through an ESP / Gmail API and schedule it | ../email-connector/SKILL.md, ../google-workspace/SKILL.md |
You own the recurring opted-in publication and its open/click/growth system. The plumbing under every send and the page that captures the signup are someone else's.
The metric truth after Apple MPP
Apple Mail Privacy Protection pre-fetches the tracking pixel, firing an "open" even when nobody read the email. It accounts for ~49% of all tracked opens and inflates reported open rate by ~15–35% on iOS-heavy lists — one beehiiv newsletter jumped from a 28% to a 55% open rate with zero behavior change. So stop steering on open rate. MPP does not touch link tracking, which is why the click is now the honest signal.
What ships with it
5 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.
- 7d ago First seen · 153 lines · 80 tokens per session scan A 89d88a1f5000
newsletter is a skill published in the GitHub repository ericrisco/rsc-harness (81 stars, last pushed today), licensed MIT. It adds 80 tokens to every session and 2,762 once invoked, about $0.0004 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 2026-09-03.
Other skills, from other repositories
landing-page-copy-writer
Writes the complete copy for a newsletter subscribe page — headline, subheadline, value proposition, social proof block, what-to-expect section, and call-to-action button text — optimised for conversion without resorting to hype or false urgency.
build-subgraph
Traverses a full graph and returns a bounded subgraph around one target node -- its depth-bounded dependencies plus any disputed claims attached to it -- while proving everything else was left out.
merge-aliases
Folds two surface names for the same backend system into one canonical entity, keeping every original mention individually retrievable, and refuses to merge pairs that only share spelling.
anchor-and-lock
Consults a check that sits outside the loop system before finalizing any decision the frozen facts bear on, and refuses every attempt by a loop to rewrite a node marked frozen, regardless of how convergent the loop's own reasoning looks.
arbitrate-collision
Detects when two loops have proposed conflicting writes to the same node and field at close to the same time, applies a stated priority rule to accept exactly one, and records the rejected write with the reason it lost.
audit-sweep
Reviews a full set of the main loop's outputs together, from a wider vantage than any single one of them, looking specifically for cross-item patterns that a one-item-at-a-time loop is structurally unable to notice.