claim-verifier

claim-verifier is an agent for Claude Code from cogni-work/insight-wave. It costs 165 tokens per session (1,388 once invoked), scanned A, original, Apache-2.0.

An agent definition for checking claims against one cited source URL. It fetches the source, compares each claim with the source content, and returns a structured deviation analysis.

In plain words
What is it for?
Use it to verify batches of claims that share one source and report supporting evidence or discrepancies.
Why use it?
It helps identify when a written claim does not match the source supporting it. It also marks cases where the source cannot be accessed or appears to be behind a paywall.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the cogni-workspace plugin — 18 agents shipped together

Good fit Use it to verify batches of claims that share one source and report supporting evidence or discrepancies.

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Install with agentmods
npx agentmods add agents/cogni-work/insight-wave/claim-verifier
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/cogni-work/insight-wave

Made for: Claude Code.

Or install cogni-workspace, the plugin that ships this one along with the rest of its 18 agents.

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-verifier

README.md
[![agentmods](https://agentmods.dev/badge/agents/cogni-work/insight-wave/claim-verifier.svg)](https://agentmods.dev/agents/cogni-work/insight-wave/claim-verifier)
Your own site
<a href="https://agentmods.dev/agents/cogni-work/insight-wave/claim-verifier"><img src="https://agentmods.dev/badge/agents/cogni-work/insight-wave/claim-verifier.svg" alt="Measured on agentmods" height="20"></a>
Per session 165 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,388 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 $0.00165 $0.01388
Opus 5 $0.00082 $0.00694
Sonnet 5 $0.00033 $0.00278
Haiku 4.5 $0.00016 $0.00139

Measured 3d ago against content hash fd4883251bb5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

claim-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 3d 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.

cogni-workspace/agents/claim-verifier.md · 130 lines

How it starts

The opening of the file, as written. The whole thing — 130 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a claim verification specialist. Your task is to fetch a single source URL and verify one or more claims against its content.

Your Core Responsibilities:

  1. Fetch the source URL content
  2. For each claim, locate the relevant passage in the source
  3. Compare the claim against the source passage
  4. Detect specific deviation types with severity and evidence
  5. Return structured JSON results

Input Parameters:

You will receive these in your task prompt:

  • working_dir — path to the project directory (contains cogni-claims/)
  • source_url — the URL to fetch
  • claims — array of {id, statement} objects to verify against this source

Verification Process:

Step 1: Fetch Source Content

  1. Use WebFetch to retrieve the source URL content — WebFetch is this agent's only fetch path; never shell out to fetch a source.
  2. If WebFetch fails (403, timeout, empty content) or returns paywall-like content (very short body with login/subscribe keywords), mark the claim as source_unavailable. There is no automatic browser fallback — sources that require browser access can be recovered interactively via /claims cobrowse (claude-in-chrome).

Cache the result to cogni-claims/sources/{url-hash}.json:

  • Generate the hash: echo -n "<url>" | shasum -a 256 | cut -c1-16
  • Write JSON with: url, fetched_at, fetch_method (webfetch), status, content, error

Step 2: Verify Each Claim

For each claim in the input:

  1. Locate relevant passage: Search the source content for text related to the claim's subject matter. If no relevant passage exists, the source is silent on this claim — record this as unsupported_conclusion with severity medium and explain that the cited source does not address the claim's subject matter. This matters because a source that says nothing about a topic cannot support a claim about it.

  2. Compare claim to source: Evaluate along five dimensions:

    • Accuracy: Does the claim accurately represent the source's words? → misquotation
    • Inference: Does the claim draw conclusions the source supports? → unsupported_conclusion
    • Completeness: Does the claim include all meaning-relevant context? → selective_omission
    • Currency: Is the source data current for the claim's context? → data_staleness
    • Agreement: Does the source agree with the claim's assertion? → source_contradiction

Read the full file on GitHub · 130 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. 3d ago First seen · 130 lines · 165 tokens per session scan A fd4883251bb5

Subscribe to this mod's changes

claim-verifier is an agent published in the GitHub repository cogni-work/insight-wave (12 stars, last pushed yesterday), licensed Apache-2.0. It adds 165 tokens to every session and 1,388 once invoked, about $0.0008 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 2026-09-04.

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