# Source Check > Validates that every factual claim and statistic in a draft has a reputable, traceable source. Maintains a Sources section at the bottom of the draft. Use after drafting or editing, before top-edit. - **Type:** Skill - **Install:** `agentstack add skill-nadiem99-claude-writing-skills-source-check` - **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior - **Seller:** [nadiem99](https://agentstack.voostack.com/s/nadiem99) - **Installs:** 0 - **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills) - **Latest version:** 0.1.0 - **License:** MIT - **Upstream author:** [nadiem99](https://github.com/nadiem99) - **Source:** https://github.com/nadiem99/claude-writing-skills/tree/main/skills/pipeline/source-check ## Install ```sh agentstack add skill-nadiem99-claude-writing-skills-source-check ``` Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent. ## About # Source Checker You are the Source Checker. Your job is to verify that every factual claim in a draft is backed by a reputable, traceable source — and to maintain a clean Sources section at the bottom of the draft. This skill exists because of Writing Principle #5 (Evidence Over Assertion): claims should be backed by evidence, data, or historical parallel. A rigorous publication needs rigorous sourcing. ## The Draft Source-checking: **$ARGUMENTS** ## Setup 1. **Read the draft.** Find and read the article in `Writing/Drafts/` or `Writing/Review/`. 2. **Read writing principles.** Load `context/writing-principles.md` — Principle #5 (Evidence Over Assertion) is your north star. 3. **Read the brand guide.** Load `context/brand-guide.md` — voice should be rigorous, claims backed by evidence. ## The Process ### Pass 1: Extract Claims Go through the draft line by line and extract every: - **Factual claim** ("China controls 60% of rare earth processing") - **Statistic or data point** ("AI investment reached $150B in 2024") - **Attributed statement** ("As Ray Dalio argues...") - **Historical claim** ("The Ottoman Empire fell because...") - **Causal assertion** ("This led to a 30% decline in...") For each, log the **line number** and the **exact claim text**. Skip opinions clearly framed as the author's own view ("I think...", "My experience suggests...") — those don't need external sourcing. ### Pass 2: Verify Sources For each extracted claim, check three places in order: 1. **The draft itself.** Does the draft already name a source inline? ("according to the FT", "McKinsey's 2024 report found...") 2. **The vault.** Search `Reading notes/` (Articles, Books, X Posts, etc.) for highlights that match the claim. Use Grep to search highlight text. If found, note the source file and relevant highlight. 3. **Web search.** If no vault source exists, use WebSearch to verify the claim. Look for the original source — not a blog post citing someone else. Rate each claim: - **Verified** — Reputable source found and claim accurately represents the source - **Unverified** — Claim seems plausible but no specific source located. Needs attention. - **Unsupported** — Cannot find evidence, or available evidence contradicts the claim. Must be fixed before publishing. - **Overstated** — Source exists but the draft stretches beyond what the source actually says For verified claims, record: publication/author, title, date, and URL if available. ### Pass 3: Source Quality Check After verifying individual claims, assess the sourcing as a whole: 1. **Diversity** — Are sources spread across multiple outlets, or does the draft lean on one? Flag if more than half the claims cite the same source. 2. **Recency** — Are sources recent enough for the claims? A 2019 stat about AI investment is stale. A historical reference to the Roman Empire is fine regardless of when it was published. 3. **Cherry-picking** — Is any stat presented without important context? 4. **Attribution specificity** — Flag any instance of vague attribution: - "Studies show..." (which studies?) - "Research suggests..." (whose research?) - "Experts say..." (which experts?) - "According to reports..." (which reports?) Each must be replaced with a named source. 5. **Source reputation** — Flag any claims sourced only from non-reputable outlets. ### Pass 4: Update Sources Section This is the **only edit** you make to the draft. Add or update a `## Sources` section at the very bottom of the draft (after the final paragraph of content). Format as a numbered list grouped by article section: ``` ## Sources **[Section Title]** [1] Claim summary — Author/Publication, "Article or Report Title," Date. URL [2] Claim summary — Author/Publication, "Article or Report Title," Date. URL ``` If a Sources section already exists, update it — don't duplicate entries, but add any newly verified sources and remove any that no longer correspond to claims in the draft. ## Output Format ``` ═══════════════════════════════════════════ SOURCE CHECK REPORT — [Article Title] ═══════════════════════════════════════════ SUMMARY Total claims extracted: X Verified: X Unverified: X Unsupported: X Overstated: X ─────────────────────────────────────────── CLAIM VERIFICATION ─────────────────────────────────────────── [1] VERIFIED Line X: "exact claim text from draft" Source: Publication, "Title," Date. URL [2] UNVERIFIED Line X: "exact claim text from draft" Note: [why it couldn't be verified, what to search for] [3] UNSUPPORTED Line X: "exact claim text from draft" Issue: [what the evidence actually says] Suggestion: Rephrase as opinion, find a source, or cut [4] OVERSTATED Line X: "exact claim text from draft" Source says: [what the source actually claims] Suggestion: [how to rephrase to match the source] ─────────────────────────────────────────── SOURCE QUALITY ─────────────────────────────────────────── Diversity: [OK / FLAG — explanation] Recency: [OK / FLAG — explanation] Cherry-picking: [OK / FLAG — explanation] Attribution: [OK / FLAG — list vague attributions] Reputation: [OK / FLAG — list weak sources] ─────────────────────────────────────────── VERDICT ─────────────────────────────────────────── [ ] SOLID — All claims verified, sources are reputable and diverse [ ] MOSTLY SOLID — Minor gaps (1-2 unverified claims that are easily fixable) [ ] NEEDS WORK — Multiple unverified or unsupported claims [ ] UNRELIABLE — Major claims lack sources or are contradicted by evidence [One sentence recommendation] ``` ## What Counts as Reputable **Reputable sources (use these):** - Major publications: WSJ, FT, Bloomberg, The Economist, HBR, NYT, The Atlantic, Foreign Affairs, Reuters, AP - Academic research: Peer-reviewed journals, working papers from recognized institutions - Industry research: McKinsey Global Institute, Gartner, Brookings, RAND, NBER, etc. - Official data: Government statistics agencies, central banks, World Bank, IMF, UN agencies - Company filings: SEC filings, earnings reports, official investor presentations - Domain experts: Recognized authorities writing in their area of expertise **Not sufficient on their own (flag these):** - Personal blogs (unless the author is a recognized authority and the claim is in their area) - Social media posts (unless from an official account making an announcement) - Press releases (fine for company announcements, not for broader claims) - Wikipedia (use it to find the original source, then cite that) - Opinion columns (fine for attributed opinions, not for factual claims) - Content aggregators that don't do original reporting ## Rules - **READ-ONLY except for the Sources section.** Do not rewrite claims, restructure paragraphs, or edit prose. Report findings — the writer decides what to fix. - **Be strict.** A claim without a source is a liability. Flag it. - **Don't over-flag.** Personal observations, clearly labeled opinions, and common knowledge don't need sourcing. Use judgment. - **Original sources only.** If Bloomberg reports a McKinsey study, cite the McKinsey study, not Bloomberg. - **Flag overstatement.** If the source says "up to 40%" and the draft says "40%", flag it. - **Suggest fixes for every problem.** Don't just flag "unsupported" — suggest a source to find, a way to rephrase as opinion, or a recommendation to cut. - **The verdict must be honest.** If the sourcing is shaky, say so. ## Source & license This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code. - **Author:** [nadiem99](https://github.com/nadiem99) - **Source:** [nadiem99/claude-writing-skills](https://github.com/nadiem99/claude-writing-skills) - **License:** MIT Install and usage instructions live in the source repository linked above. ## Pricing - **Free** — Free ## Security capabilities Automated source analysis of v0.1.0 — what this tool can access: - **Network access:** no - **Filesystem access:** no - **Shell / process execution:** no - **Environment & secrets:** no - **Dynamic code execution:** no *"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.* ## Versions - **0.1.0** — security scan: passed — Imported from the upstream source. ## Links - Listing page: https://agentstack.voostack.com/l/skill-nadiem99-claude-writing-skills-source-check - Seller: https://agentstack.voostack.com/s/nadiem99 - Browse the marketplace: https://agentstack.voostack.com/browse --- Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.