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 caelum29/calibre-mcp --skill calibre-distillgit clone --depth 1 https://github.com/caelum29/calibre-mcpWrote 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/caelum29/calibre-mcp/calibre-distill)<a href="https://agentmods.dev/skills/caelum29/calibre-mcp/calibre-distill"><img src="https://agentmods.dev/badge/skills/caelum29/calibre-mcp/calibre-distill/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/caelum29/calibre-mcp/calibre-distill"><img src="https://agentmods.dev/badge/skills/caelum29/calibre-mcp/calibre-distill.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 | $0.00151 | $0.06909 |
| Opus 5 | $0.00076 | $0.03454 |
| Sonnet 5 | $0.00030 | $0.01382 |
| Haiku 4.5 | $0.00015 | $0.00691 |
Grade C, and why
calibre-distill scanned grade C with 1 finding 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 11d 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.
Hidden instructionshighPrompt injection
Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.
<!-- Re-author a minimal example that demonstrates the same technique — fresh variable names, a fresh scenario. API/config identifiers and syntax rules are facts and stay exact; the author's example code does NOT get cop How it starts
The opening of the file, as written. The whole thing — 599 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Calibre Distill
Turn a book already in your Calibre library into an actionable agent skill by extracting its structure — not producing summaries. The calibre-mcp server supplies the chapter map and in-book search; the host agent (this LLM) does all synthesis.
Philosophy
Books contain crystallized expertise: frameworks, principles, and techniques that took years to develop. This skill extracts that knowledge into a format a compatible agent can leverage repeatedly.
Extract structure, not summaries. A skill isn't a book report. It's a toolkit of:
- Named frameworks (mental models with clear application)
- Actionable principles (rules that guide decisions)
- Techniques (step-by-step methods)
- Anti-patterns (what to avoid and why)
- Voice calibration (how the author thinks and communicates)
Preserve the author's precision. "The 5 Whys" isn't interchangeable with "ask why multiple times." Capture the exact formulation.
Layer depth appropriately. Simple books → simple skills. Complex books with 10+ frameworks → skills with reference files and on-demand chapters.
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.
- 11d ago First seen · 599 lines · 151 tokens per session scan C e9a412d40c3f
calibre-distill is a skill published in the GitHub repository caelum29/calibre-mcp (14 stars, last pushed 21d ago), licensed MIT. It adds 151 tokens to every session and 6,909 once invoked, about $0.0008 per session on Opus 5. A static security scan graded it C with 1 finding (hidden instructions). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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