factchk

factchk is a skill for Claude Code from imMamdouhaboammar/get-fable. It costs 136 tokens per session (628 once invoked), scanned A, a copy of factchk, AGPL-3.0.

A fact-checking method that tests claims about what is real against outside sources in both directions. It checks claims that something is plausible, absurd, new, or impossible rather than relying on intuition.

In plain words
What is it for?
Use it before publishing reality-based statements in documents or other artifacts, including claims you are about to write.
Why use it?
It reduces errors caused by assuming unusual things cannot be true or familiar things must be true. When sources cannot be reached, it flags the claim instead of presenting a guess as fact.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the paperthin plugin — 29 skills shipped together

Good fit Use it before publishing reality-based statements in documents or other artifacts, including claims you are about to write.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/immamdouhaboammar/get-fable/factchk
Install

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.

Any agent
npx skills add imMamdouhaboammar/get-fable --skill factchk
Clone the repo
git clone --depth 1 https://github.com/imMamdouhaboammar/get-fable

Made for: Claude Code.

Or install paperthin, the plugin that ships this one along with the rest of its 29 skills.

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 factchk

README.md
[![agentmods](https://agentmods.dev/badge/skills/immamdouhaboammar/get-fable/factchk/github.svg)](https://agentmods.dev/skills/immamdouhaboammar/get-fable/factchk)
Your own site
<a href="https://agentmods.dev/skills/immamdouhaboammar/get-fable/factchk"><img src="https://agentmods.dev/badge/skills/immamdouhaboammar/get-fable/factchk/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 factchk

Your own site · 80×15
<a href="https://agentmods.dev/skills/immamdouhaboammar/get-fable/factchk"><img src="https://agentmods.dev/badge/skills/immamdouhaboammar/get-fable/factchk.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 136 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 628 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 100% copy Near-identical to another mod 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 $0.00136 $0.00628
Opus 5.5 $0.00054 $0.00251
Sonnet 5.5 $0.00027 $0.00126
Haiku 4.5 $0.00014 $0.00063

Measured 25d ago against content hash 17ff29bec3af, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

factchk 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 25d 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.

Origin

This is a copy

100% identical to factchk, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/fable-wise/skills/depth/factchk/SKILL.md · 29 lines

The source is not reproduced here

Licensed AGPL-3.0

The repository is licensed AGPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

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. 25d ago First seen · 29 lines · 136 tokens per session scan A 17ff29bec3af

Subscribe to this mod's changes

factchk is a skill published in the GitHub repository imMamdouhaboammar/get-fable (0 stars, last pushed yesterday), licensed AGPL-3.0. It adds 136 tokens to every session and 628 once invoked, about $0.0005 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to factchk, and is treated as a copy.

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