fact-checker

fact-checker is an agent for Claude Code from Pyroxin/opinionated-claude-skills. It costs 164 tokens per session (3,819 once invoked), scanned A, original, EPL-2.0.

An agent that checks whether a particular source actually supports a particular claim.

In plain words
What is it for?
Use it with a claim and a URL, file, or citation pair, or with a claim alone for a limited source check.
Why use it?
It provides a fresh review that is less likely to be influenced by the conversation in which the claim was originally made.

Agent for Claude Code

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

Part of the opinionated-research plugin — 3 skills, 3 agents shipped together

Good fit Use it with a claim and a URL, file, or citation pair, or with a claim alone for a limited source check.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/pyroxin/opinionated-claude-skills/fact-checker
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.

Clone the repo
git clone --depth 1 https://github.com/Pyroxin/opinionated-claude-skills

Made for: Claude Code.

Or install opinionated-research, the plugin that ships this one along with the rest of its 3 skills, 3 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/pyroxin/opinionated-claude-skills/fact-checker/github.svg)](https://agentmods.dev/agents/pyroxin/opinionated-claude-skills/fact-checker)
Your own site
<a href="https://agentmods.dev/agents/pyroxin/opinionated-claude-skills/fact-checker"><img src="https://agentmods.dev/badge/agents/pyroxin/opinionated-claude-skills/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/pyroxin/opinionated-claude-skills/fact-checker"><img src="https://agentmods.dev/badge/agents/pyroxin/opinionated-claude-skills/fact-checker.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 164 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,819 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 unknown 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 $0.00164 $0.03819
Opus 5 $0.00082 $0.01910
Sonnet 5 $0.00033 $0.00764
Haiku 4.5 $0.00016 $0.00382

Measured 11d ago against content hash 1ad255a1ef41, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, 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 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.

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.

opinionated-research/agents/fact-checker.md · 170 lines

The source is not reproduced here

Licensed EPL-2.0

The repository is licensed EPL-2.0, 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. 11d ago First seen · 170 lines · 164 tokens per session scan A 1ad255a1ef41

Subscribe to this mod's changes

fact-checker is an agent published in the GitHub repository Pyroxin/opinionated-claude-skills (9 stars, last pushed 4d ago), licensed EPL-2.0. It adds 164 tokens to every session and 3,819 once invoked, about $0.0008 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.

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