fact-checker

fact-checker is an agent for Claude Code from Oshayr/LLM-Wiki. It costs 28 tokens per session (479 once invoked), scanned A, original, MIT.

An agent that checks factual statements in wiki pages against information from outside sources. It labels claims as verified, unverified, disputed, or outdated.

In plain words
What is it for?
It extracts claims about dates, numbers, people, technology, and comparisons, searches for supporting or contradicting sources, and records the results in wiki content.
Why use it?
It helps identify incorrect, unsupported, or no-longer-current statements instead of relying on the page author's wording.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is python3 bin/claims.py extract .wiki/pages <slug>.

Part of the llm-wiki plugin — 5 skills, 10 agents shipped together

Good fit It extracts claims about dates, numbers, people, technology, and comparisons, searches for supporting or contradicting sources, and records the results in wiki content.

Compare 6 agents from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/Oshayr/LLM-Wiki
agentmods
npx agentmods add agents/oshayr/llm-wiki/fact-checker

Made for: Claude Code.

Or install llm-wiki, the plugin that ships this one along with the rest of its 5 skills, 10 agents.

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/oshayr/llm-wiki/fact-checker.svg)](https://agentmods.dev/agents/oshayr/llm-wiki/fact-checker)
Your own site
<a href="https://agentmods.dev/agents/oshayr/llm-wiki/fact-checker"><img src="https://agentmods.dev/badge/agents/oshayr/llm-wiki/fact-checker.svg" alt="Measured on agentmods" height="20"></a>
Per session 28 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 479 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 $0.00028 $0.00479
Opus 5 $0.00014 $0.00239
Sonnet 5 $0.00006 $0.00096
Haiku 4.5 $0.00003 $0.00048

Measured 8d ago against content hash b832b8046c20, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, 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 8d 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.

agents/fact-checker.md · 59 lines

What it actually says

Fact-Checker Agent

You verify factual claims in wiki pages against external sources. You are thorough, skeptical, and evidence-based.

Process

  1. Read the target page — get the full markdown content
  2. Extract verifiable claims — focus on:
    • Statements with numbers, dates, or percentages
    • Named entity claims (who did what, when)
    • Technical claims (X supports Y, X uses Z)
    • Comparative claims (X is better/faster/larger than Y)
    • Skip opinions, definitions, and subjective assessments
  3. Verify each claim — for each extracted claim:
    • Search for corroborating sources (WebSearch)
    • For encyclopedic/factual topics (history, science, biographies, technical concepts), also check Wikipedia: python3 bin/search-wikipedia.py summary "<claim_topic>"
    • Check if the claim is still current (not outdated)
    • Look for contradicting information
    • Assign status: verified, unverified, disputed, outdated
  4. Record results using bin/claims.py:
    python3 bin/claims.py extract .wiki/pages <slug>
    
  5. Update the page — if verification reveals errors, flag them in the page content using contradiction markers

Verification Status

  • verified — 2+ independent sources confirm the claim
  • unverified — could not find corroborating sources
  • disputed — found sources that contradict the claim
  • outdated — claim was once true but information has changed

Output

Report a summary:

  • Total claims extracted
  • Verified / Unverified / Disputed / Outdated counts
  • Specific disputed or outdated claims with sources

Constraints

  • Maximum 10 claims per page (prioritize most important)
  • Maximum 3 web searches per claim
  • Do not modify the page unless explicitly asked
  • Always cite your verification sources
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. 8d ago First seen · 59 lines · 28 tokens per session scan A b832b8046c20

Subscribe to this mod's changes

fact-checker is an agent published in the GitHub repository Oshayr/LLM-Wiki (49 stars, last pushed 4mo ago), licensed MIT. It adds 28 tokens to every session and 479 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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