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 BigCactusLabs/dead-letter --skill dead-letter-contextgit clone --depth 1 https://github.com/BigCactusLabs/dead-letterWrote 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/bigcactuslabs/dead-letter/dead-letter-context)<a href="https://agentmods.dev/skills/bigcactuslabs/dead-letter/dead-letter-context"><img src="https://agentmods.dev/badge/skills/bigcactuslabs/dead-letter/dead-letter-context/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/bigcactuslabs/dead-letter/dead-letter-context"><img src="https://agentmods.dev/badge/skills/bigcactuslabs/dead-letter/dead-letter-context.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00040 | $0.01577 |
| Opus 5 | $0.00020 | $0.00788 |
| Sonnet 5 | $0.00008 | $0.00315 |
| Haiku 4.5 | $0.00004 | $0.00158 |
Grade A, and why
dead-letter-context 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 10d 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.
The source is not reproduced here
A licence we could not identify
The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.
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.
- 10d ago First seen · 97 lines · 40 tokens per session scan A 4796e66007e7
dead-letter-context is a skill published in the GitHub repository BigCactusLabs/dead-letter (7 stars, last pushed 3d ago), with no licence file. It adds 40 tokens to every session and 1,577 once invoked, about $0.0002 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 2026-08-31.
Other skills, from other repositories
sign-draft
Author a new SIGN document from a concept, notes, or requirements — interactively and spec-compliant. Use when an operator asks Claude Code to write, draft, or create a SIGN document (a std / pol / ref / proc / xwalk doc), produce a Layer 1 index entry, or hand-write SIGN structure. For converting an EXISTING source…
sign-ingest
Use this skill when an operator asks Claude Code to convert source documents into SIGN using this repository's sign-ingest CLI.
docx2md
Convert Word (.docx) files to high-fidelity Markdown. Preserves tables (including vMerge), footnotes, field-code references, bibliography SDT blocks, numbered/bullet lists, images, and YAML frontmatter. Use when asked to convert a Word document to Markdown, extract text from .docx, parse a Word file for further…
wechat-article-to-markdown
A skill that fetches articles from WeChat Official Accounts and converts them to Markdown, a plain-text format commonly used for documentation.
officecli-academic-paper
Use this skill to build academic-style .docx output: journal / conference / thesis chapters carrying formal citation style (APA, Chicago, IEEE, MLA), numbered equations, figure & table cross-references, footnotes/endnotes, bibliography, or multi-column journal layout. Trigger on: 'research paper', 'journal paper'…
officecli-word-form
Use this skill to create fillable Word forms (.docx) with real Content Controls (SDT) + legacy FormField checkboxes + MERGEFIELD mail-merge placeholders + document protection. Trigger on: 'fillable form', 'form fields', 'content controls', 'SDT', 'word form', 'fill in', 'only editable fields', 'protect document'…