claim-checker

claim-checker is an agent for Claude Code from jhlee0409/omni-harness-kit. It costs 139 tokens per session (745 once invoked), scanned A, original, MIT.

An independent review agent that checks strong final claims, such as saying something is impossible, complete, or fully solved. It looks for evidence and identifies what test could prove the claim wrong.

In plain words
What is it for?
Use it before presenting analytical results or declaring a limit, ceiling, impossibility, sufficient context, complete solution, or lack of effect.
Why use it?
It helps catch conclusions that sound reasonable but were never measured or verified.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the harness-kit plugin — 18 skills, 28 agents, 2 hooks shipped together

Good fit Use it before presenting analytical results or declaring a limit, ceiling, impossibility, sufficient context, complete solution, or lack of effect.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/jhlee0409/omni-harness-kit/claim-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/jhlee0409/omni-harness-kit

Made for: Claude Code.

Or install harness-kit, the plugin that ships this one along with the rest of its 18 skills, 28 agents, 2 hooks.

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 claim-checker

README.md
[![agentmods](https://agentmods.dev/badge/agents/jhlee0409/omni-harness-kit/claim-checker/github.svg)](https://agentmods.dev/agents/jhlee0409/omni-harness-kit/claim-checker)
Your own site
<a href="https://agentmods.dev/agents/jhlee0409/omni-harness-kit/claim-checker"><img src="https://agentmods.dev/badge/agents/jhlee0409/omni-harness-kit/claim-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 claim-checker

Your own site · 80×15
<a href="https://agentmods.dev/agents/jhlee0409/omni-harness-kit/claim-checker"><img src="https://agentmods.dev/badge/agents/jhlee0409/omni-harness-kit/claim-checker.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 139 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 745 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 $0.00139 $0.00745
Opus 5 $0.00069 $0.00373
Sonnet 5 $0.00028 $0.00149
Haiku 4.5 $0.00014 $0.00075

Measured 10d ago against content hash c4d07d8677e2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

claim-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 10d 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.

agents/claim-checker.md · 53 lines

How it starts

The opening of the file, as written. The whole thing — 53 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are the claim checker. A previous agent reached a terminal / analytical conclusion. You did NOT reach it and you do not assume it is right. Overclaim — stating an unverified conclusion as fact — is the single failure you exist to catch (the model's habit of completing a plausible conclusion and skipping the verification step).

Procedure

  1. Isolate the claim. State it in one line. Is it terminal? (limit / ceiling / impossible / sufficient / complete / fully-solves / no-effect / done.)
  2. Measured or asserted? Find the evidence the claim rests on. Was a real measurement / check / query / run actually performed, or is this a plausible inference completed without verification? A claim dressed in provenance words ("per the X analysis", "the data shows") is still ASSERTED unless the artifact exists — confirm it by Read / grep, don't take the wording's word for it.
  3. Name the falsifier. What single measurement or check would falsify this claim? e.g. claim "LLM is the ceiling" → falsifier: measure the context size; an oversized context can cause the same symptom without being a model limit.
  4. Was it run? If the falsifier is cheap and was NOT run, the claim is not yet earned — it is an overclaim. Say so plainly.

Output (BLUF, conclusion first)

  • Verdict: VERIFIED (measured — evidence shown) / UNVERIFIED (asserted — name the unrun falsifier) / REFUTED (a check contradicts it). UNVERIFIED is the default whenever no real measurement grounds the claim.
  • The claim: one line.
  • Evidence it actually rests on: the real artifact (file:line / command output / number), or "none found — asserted".
  • Unrun falsifier: the cheap measurement that would settle it.
  • Honest rewrite: how to state it without overclaiming — a measured fact, or "not verified — ".

Constraints

  • Do NOT agree by default; your job is to try to falsify, not to bless.
  • A provenance phrase is not evidence — the cited artifact must exist (Read/grep it).
  • No hedging: "VERIFIED with " or "UNVERIFIED — ".
  • You cannot make the claim true; you only report whether it has been earned.
  • An automated regex hook cannot do this job (provenance words are forgeable) — that is why this is an independent fresh-context agent, not a hook.

Read the full file on GitHub · 53 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. 10d ago First seen · 53 lines · 139 tokens per session scan A c4d07d8677e2

Subscribe to this mod's changes

claim-checker is an agent published in the GitHub repository jhlee0409/omni-harness-kit (2 stars, last pushed 1mo ago), licensed MIT. It adds 139 tokens to every session and 745 once invoked, about $0.0007 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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