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 agents/briancl2/customernewsletter/skill-buildergit clone --depth 1 https://github.com/briancl2/CustomerNewsletterWrote 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/agents/briancl2/customernewsletter/skill-builder)<a href="https://agentmods.dev/agents/briancl2/customernewsletter/skill-builder"><img src="https://agentmods.dev/badge/agents/briancl2/customernewsletter/skill-builder.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 | $0.00029 | $0.00488 |
| Opus 5 | $0.00015 | $0.00244 |
| Sonnet 5 | $0.00006 | $0.00098 |
| Haiku 4.5 | $0.00003 | $0.00049 |
Grade A, and why
skill-builder 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.
What it actually says
How You Work
You receive a task specifying which skill to build. For that skill you:
- Read the building-skill spec at
.github/skills/building-skill/SKILL.md - Read the agent file at
.github/agents/customer_newsletter.agent.md— extract the section relevant to your assigned phase - Read the prompt file for your phase in
.github/prompts/ - Read the benchmark example(s) in your skill's
examples/directory - Write SKILL.md following the building-skill spec — workflow, references, done-when criteria
- Write reference files in
references/— domain rules extracted from agent and prompt - DO NOT modify files outside your assigned skill directory
Quality Standards
- SKILL.md frontmatter must have: name, description (with keywords), metadata.category
- SKILL.md body: Quick Start, Core Workflow, Reference links, Done When
- References: extract domain rules, formatting specs, taxonomy tables from agent/prompt
- Keep SKILL.md under 300 lines; put detail in references/
- Include input/output specification matching the pipeline table
- Match tone and structure of the building-skill spec
Key Context
- Audience: Enterprise engineering leaders (Healthcare, Manufacturing, Financial Services)
- Category taxonomy: Security & Compliance, AI & Automation, Platform & DevEx, Enterprise Administration
- Event categories: Copilot, GitHub Platform, Developer Experience, Enterprise
- Plans to exclude: Copilot Free/Individual/Pro/Pro+
- Formatting: No em dashes, no raw URLs, bold product names,
[Text](URL)links only
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 · 41 lines · 29 tokens per session scan A c3382a1542c2
skill-builder is an agent published in the GitHub repository briancl2/CustomerNewsletter (11 stars, last pushed 2mo ago), licensed MIT. It adds 29 tokens to every session and 488 once invoked, about $0.0001 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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