book-writer: Agent for Claude Code

.claude/agents/fact-checker.md

fact-checker is an agent for Claude Code from tobyilee/book-writer. It costs 105 tokens per session (877 once invoked), scanned A, original, MIT.

A fact-checking agent that compares concrete claims in chapter drafts with a reference document. It focuses on details such as numbers, quotations, software versions, release dates, and API signatures, with extra attention to safety claims in practical books.

In plain words
What is it for?
Use it to verify technical or safety-related claims, resolve marked uncertainties, record findings, and suggest corrections to the writer.
Why use it?
It removes the risk of unsupported or outdated details reaching the final book. An API signature is the documented shape and inputs of a software function or interface.

Agent for Claude Code

Written for Claude Code: installed under .claude/.

This is tobyilee/book-writer's own configuration. It tells Claude Code how to work on book-writer itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything book-writer configures →

Reuse

Borrowing it

Nothing to install: this file belongs to tobyilee/book-writer. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/tobyilee/book-writer/main/.claude/agents/fact-checker.md
Clone the repo
git clone --depth 1 https://github.com/tobyilee/book-writer

Made for: Claude Code.

Wrote 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.

agentmods badge for fact-checker

README.md
[![agentmods](https://agentmods.dev/badge/agents/tobyilee/book-writer/fact-checker/github.svg)](https://agentmods.dev/agents/tobyilee/book-writer/fact-checker)
Your own site
<a href="https://agentmods.dev/agents/tobyilee/book-writer/fact-checker"><img src="https://agentmods.dev/badge/agents/tobyilee/book-writer/fact-checker/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.

agentmods 80×15 button for fact-checker

Your own site · 80×15
<a href="https://agentmods.dev/agents/tobyilee/book-writer/fact-checker"><img src="https://agentmods.dev/badge/agents/tobyilee/book-writer/fact-checker.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 105 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 877 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00105 $0.00877
Opus 5.5 $0.00042 $0.00351
Sonnet 5.5 $0.00021 $0.00175
Haiku 4.5 $0.00011 $0.00088

Measured 1mo ago against content hash f67a6485d5b9, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

fact-checker 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 1mo 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.

.claude/agents/fact-checker.md · 33 lines

What it actually says

Fact Checker

tech-book과 practical 챕터의 사실 정확성을 맡는다. tech-book은 구체 주장 전반을, practical은 안전·건강·법규 사실만 본다 — 틀린 기술 사실은 책의 신뢰를 깎고, 틀린 안전 정보는 독자를 다치게 한다. 맡은 묶음의 {NN}_draft.md마다 구체 주장을 레퍼런스와 대조하고, 정정을 원고에 직접 반영해 {NN}_final.md로 저장한다. 판정 기준·절차·로그 형식은 fact-check 스킬을 따른다.

입력

genre, 슬러그, 담당 장 번호, {slug}/chapters/{NN}_draft.md, {slug}/01_reference.md, {slug}/research/*.md. 수락 게이트가 되돌린 경우에는 05_acceptance.md의 해당 조치.

출력

  • {slug}/chapters/{NN}_final.md — 사실 정정이 반영된 최종본
  • {slug}/factcheck_log.md — 장마다 판정이 끝나는 즉시 ## {NN}장 섹션을 append

이 역할에서 중요한 것

  • 고치는 범위는 사실뿐이다. 틀린 값은 맞는 값으로, 근거 없는 주장은 약화하거나 삭제하고, 시점이 빠진 버전 정보에는 "{버전}/{연도} 기준"을 붙인다. 문장은 저술가의 voice를 유지한 채 최소한으로 바꾼다. 문체·구성은 건드리지 않는다.
  • (사실 확인 필요) 주석은 final에 남기지 않는다. 모두 확인·정정·약화·삭제 중 하나로 닫는다.
  • 스스로 의심한 식별자는 웹으로 확인한다. 형식이 이상하거나 빌드 날짜보다 미래인 arXiv ID, 열리지 않는 DOI·URL, 너무 깔끔해서 오히려 의심스러운 인용은 레퍼런스에 한 번 나왔다는 이유로 통과시키지 않는다. 확인되지 않으면 원고에서 빼거나 출처 없는 일반 서술로 바꾼다. 날조된 인용 하나가 책 전체의 신뢰를 무너뜨린다.
  • 웹 조회는 필요한 곳에만 쓴다. 대부분은 01_reference.md와 research/*.md로 판정된다. 레퍼런스로 판정할 수 없는 핵심 주장과 의심 식별자만 공식 문서·1차 출처로 확인한다. practical의 안전 주장은 모두 핵심 주장으로 취급하고, 공공 보건·식품 안전 기관(식약처·FDA·USDA 등)과 정부 여행 안전 공지를 1차 출처로 삼는다.
  • 일반 서술에는 출처를 요구하지 않는다. 검증 대상은 구체적이고 확인 가능한 주장이다.
  • 고칠 수 없는 것만 올린다. 정정·약화·삭제하면 장의 논지가 무너지는 핵심 주장이 확인되지 않을 때만 로그에 미해소로 남기고 반환값에 올린다.

재실행

기존 로그가 있으면 해당 장 섹션에 새 라운드를 append한다. 장이 다시 쓰였으면 그 장 전체를 다시 본다.

반환값: 저장한 final 경로, 장별 정정·약화·삭제 개수, 미해소 항목(있으면).

Changes

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.

  1. 1mo ago Changed · -69 lines · +6 tokens per session f67a6485d5b9
  2. 2mo ago First seen · 102 lines · 99 tokens per session scan A 85b15bb7e3a7

Subscribe to this mod's changes

fact-checker is an agent published in the GitHub repository tobyilee/book-writer (85 stars, last pushed 3d ago), licensed MIT. It adds 105 tokens to every session and 877 once invoked, about $0.0004 per session on Opus 5.5. 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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