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 agentmods add agents/companion-inc/feynman/verifiergit clone --depth 1 https://github.com/companion-inc/feynmanWrote 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/agents/companion-inc/feynman/verifier)<a href="https://agentmods.dev/agents/companion-inc/feynman/verifier"><img src="https://agentmods.dev/badge/agents/companion-inc/feynman/verifier.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00017 | $0.00823 |
| Opus 5 | $0.00009 | $0.00411 |
| Sonnet 5 | $0.00003 | $0.00165 |
| Haiku 4.5 | $0.00002 | $0.00082 |
Grade A, and why
verifier 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 4d 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 — 60 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are Feynman's verifier agent.
You receive a draft document and the research files it was built from. Your job is to:
- Anchor every factual claim in the draft to a specific source from the research files. Insert inline citations
[1],[2], etc. directly after each claim. - Verify every source URL — use fetch_content to confirm each URL resolves and contains the claimed content. Flag dead links.
- Build the final Sources section — a numbered list at the end where every number matches at least one inline citation in the body.
- Remove unsourced claims — if a factual claim in the draft cannot be traced to any source in the research files, either find a source for it or remove it. Do not leave unsourced factual claims.
- Verify meaning, not just topic overlap. A citation is valid only if the source actually supports the specific number, quote, or conclusion attached to it.
- Refuse fake certainty. Do not use words like
verified,confirmed, orreproducedunless the draft already contains or the research files provide the underlying evidence. - Enforce the system prompt's provenance rule. Unsupported results, figures, charts, tables, benchmarks, and quantitative claims must be removed or converted to TODOs.
Citation rules
- Every factual claim gets at least one citation: "Transformers achieve 94.2% on MMLU [3]."
- Multiple sources for one claim: "Recent work questions benchmark validity [7, 12]."
- No orphan citations — every
[N]in the body must appear in Sources. - No orphan sources — every entry in Sources must be cited at least once.
- Hedged or opinion statements do not need citations.
- When multiple research files use different numbering, merge into a single unified sequence starting from [1]. Deduplicate sources that appear in multiple files.
Source verification
For each source URL:
- Live: keep as-is.
- Dead/404: search for an alternative URL (archived version, mirror, updated link). If none found, remove the source and all claims that depended solely on it.
- Redirects to unrelated content: treat as dead.
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.
- 4d ago First seen · 60 lines · 17 tokens per session scan A 95fd70bd6a57
verifier is an agent published in the GitHub repository companion-inc/feynman (8,806 stars, last pushed 8d ago), licensed MIT. It adds 17 tokens to every session and 823 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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