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.
npx skills add axiomantic/spellbook --skill fact-checkinggit clone --depth 1 https://github.com/axiomantic/spellbookWrote 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.
[](https://agentmods.dev/skills/axiomantic/spellbook/fact-checking)<a href="https://agentmods.dev/skills/axiomantic/spellbook/fact-checking"><img src="https://agentmods.dev/badge/skills/axiomantic/spellbook/fact-checking/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.
<a href="https://agentmods.dev/skills/axiomantic/spellbook/fact-checking"><img src="https://agentmods.dev/badge/skills/axiomantic/spellbook/fact-checking.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 3 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Excessive Agency · line 60 Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
- medium Excessive Agency · line 200 Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
- medium Excessive Agency · line 259 Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00068 | $0.02489 |
| Opus 5.5 | $0.00027 | $0.00996 |
| Sonnet 5.5 | $0.00014 | $0.00498 |
| Haiku 4.5 | $0.00007 | $0.00249 |
Grade A, and why
fact-checking 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 263 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Evidence Hierarchy Reference
This skill follows the shared evidence hierarchy, depth escalation protocol, and mandatory inconclusive conditions defined in skills/shared-references/evidence-hierarchy.md. Verification agents must cite evidence tiers in every verdict. The depth escalation protocol governs re-verification requirements.
CoVe Self-Interrogation Reference
This skill applies the Chain-of-Verification protocol defined in skills/shared-references/cove-protocol.md during claim extraction (Phases 2-3). CoVe self-interrogation runs on synthesized or inferred claims to catch extraction errors before triage. See the shared reference for the full three-step protocol and fact-checking integration notes.
Invariant Principles
- Claims are hypotheses - Every claim requires empirical evidence before verdict
- Evidence before verdict - No verdict without traceable, citable proof
- User controls scope - User selects scope and approves all fixes
- Deduplicate within run - Re-running the same fact-check on an unchanged
scope returns the same verdicts (the
.fact-checking/state.jsoncheckpoint tracks per-claim completion; resumption checks it before re-verifying). - Learn from trajectories - Store verification trajectories in the run's checkpoint state for in-session resume; cross-session reuse is a future concern, not a current invariant.
| Pattern | Action |
|---|---|
| RESEARCH_REQUEST ("research", "check", "verify") | Dispatch research subagent |
| UNKNOWN ("don't know", "not sure") | Dispatch analysis subagent |
| CLARIFICATION (ends with ?) | Answer, then re-ask |
| SKIP ("skip", "move on") | Proceed to next item |
| </ARH_INTEGRATION> |
What ships with it
6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 1mo ago First seen · 263 lines · 68 tokens per session scan A a874a2095756
fact-checking is a skill published in the GitHub repository axiomantic/spellbook (10 stars, last pushed 2d ago), licensed MIT. It adds 68 tokens to every session and 2,489 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 2026-09-03.
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