fact-check

fact-check is a skill for Claude Code from yennanliu/InvestSkill. It costs 81 tokens per session (6,861 once invoked), scanned A, original, MIT.

A fact-checking workflow for reports and data sets. It extracts claims and figures, compares them with primary sources such as company filings or official economic data, and labels each result.

In plain words
What is it for?
Use it to verify reports, recompute derived numbers, check market or economic claims, and reissue a report with inline verification labels.
Why use it?
It helps catch incorrect figures, unsupported statements, stale data, and arithmetic errors before they appear in an analysis. It also makes the source and date for each figure clear.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: positional $N argument.

Part of the us-stock-analysis plugin — 34 skills shipped together

Good fit Use it to verify reports, recompute derived numbers, check market or economic claims, and reissue a report with inline verification labels.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/yennanliu/investskill/fact-check
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 yennanliu/InvestSkill --skill fact-check
Clone the repo
git clone --depth 1 https://github.com/yennanliu/InvestSkill

Made for: Claude Code.

Or install us-stock-analysis, the plugin that ships this one along with the rest of its 34 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 fact-check

README.md
[![agentmods](https://agentmods.dev/badge/skills/yennanliu/investskill/fact-check/github.svg)](https://agentmods.dev/skills/yennanliu/investskill/fact-check)
Your own site
<a href="https://agentmods.dev/skills/yennanliu/investskill/fact-check"><img src="https://agentmods.dev/badge/skills/yennanliu/investskill/fact-check/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-check

Your own site · 80×15
<a href="https://agentmods.dev/skills/yennanliu/investskill/fact-check"><img src="https://agentmods.dev/badge/skills/yennanliu/investskill/fact-check.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 81 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 6,861 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 $0.00081 $0.06861
Opus 5.5 $0.00032 $0.02744
Sonnet 5.5 $0.00016 $0.01372
Haiku 4.5 $0.00008 $0.00686

Measured 8d ago against content hash c8617eef93aa, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

fact-check 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.

plugins/us-stock-analysis/skills/fact-check/SKILL.md · 289 lines

How it starts

The opening of the file, as written. The whole thing — 289 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Fact Check — Verify the Numbers, Cite the Sources

⚠️ Data Verification — Do This Before Any Analysis

Before verifying anything, establish what data each claim actually needs:

  1. Fetch current price only where a claim needs it — market claims (price, market cap, yield, multiples "today") are checked against a live quote for the report's as-of date and today's; use web search or ask the user. Reported figures, historical comparisons, and --recompute runs need no live quote — do not request one, and do not let its absence block them. Never assume a price from training data.
  2. Confirm key figures — for this skill the "key figures" are the sources themselves: the filing (10-K / 10-Q / 8-K / proxy / Form 4 / 13F), the IR release, the FRED series, the exchange or issuer data, or the document the user pasted. Retrieve or request them before judging a single claim. A claim checked against memory is not checked.
  3. State your data source — fill in the Data & Sources header (next section) so the origin, as-of date, retrieval path, and confidence of every figure are explicit at the top of the output.
  4. Flag stale data explicitly — if a live quote is needed for a market claim and unavailable, display this warning before proceeding, and mark those claims ❓ or 🕒 rather than guessing:

⚠️ Live data unavailable. The following analysis uses training-data estimates which may be significantly out of date. Verify all prices and metrics before making any decisions.

The warning describes the inputs actually used: when every claim was checked against user-supplied documents, say so instead of implying training-data estimates were involved. Never silently substitute training-data estimates for current prices. When in doubt, ask the user to paste the latest quote.


📋 Data & Sources Header — Open Every Output With It

The first thing in the output is this provenance block, filled in — never left as placeholders. It is the standard documented on the Data & Accuracy page and the first thing result-validator looks for:

Read the full file on GitHub · 289 lines

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 Changed · +1 lines c8617eef93aa
  2. 24d ago Changed · +2 lines 07465d467d1e
  3. 25d ago First seen · 286 lines · 81 tokens per session scan A dc75e80b8e40

Subscribe to this mod's changes

fact-check is a skill published in the GitHub repository yennanliu/InvestSkill (250 stars, last pushed yesterday), licensed MIT. It adds 81 tokens to every session and 6,861 once invoked, about $0.0003 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 2026-09-25.

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