evidence-check

evidence-check is a skill for Claude Code from jerseycheese/agent-skills. It costs 59 tokens per session (2,812 once invoked), scanned A, original, MIT.

An evidence-checking guide for keeping an AI's claims tied to information it can actually support. It distinguishes checked facts from guesses and explains where missing evidence would need to come from.

In plain words
What is it for?
Use it to audit claims, explain how an answer is known, and respond transparently when evidence is unavailable.
Why use it?
It reduces confident-sounding errors when an answer lacks a reliable basis.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions CLAUDE.md; mentions AGENTS.md.

Part of the workflow-skills plugin — 34 skills shipped together

Good fit Use it to audit claims, explain how an answer is known, and respond transparently when evidence is unavailable.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/jerseycheese/agent-skills/evidence-check
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.

Any agent
npx skills add jerseycheese/agent-skills --skill evidence-check
Clone the repo
git clone --depth 1 https://github.com/jerseycheese/agent-skills

Made for: Claude Code.

Or install workflow-skills, the plugin that ships this one along with the rest of its 34 skills.

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 evidence-check

README.md
[![agentmods](https://agentmods.dev/badge/skills/jerseycheese/agent-skills/evidence-check/github.svg)](https://agentmods.dev/skills/jerseycheese/agent-skills/evidence-check)
Your own site
<a href="https://agentmods.dev/skills/jerseycheese/agent-skills/evidence-check"><img src="https://agentmods.dev/badge/skills/jerseycheese/agent-skills/evidence-check/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 evidence-check

Your own site · 80×15
<a href="https://agentmods.dev/skills/jerseycheese/agent-skills/evidence-check"><img src="https://agentmods.dev/badge/skills/jerseycheese/agent-skills/evidence-check.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,812 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 $0.00059 $0.02812
Opus 5.5 $0.00024 $0.01125
Sonnet 5.5 $0.00012 $0.00562
Haiku 4.5 $0.00006 $0.00281

Measured 11d ago against content hash 079c16cfec08, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

evidence-check 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 11d 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.

skills/evidence-check/SKILL.md · 283 lines

How it starts

The opening of the file, as written. The whole thing — 283 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Evidence Check

A framework for keeping an AI honest about what it actually knows, instead of dressing up guesses as established fact. The core principle: if you can't point to evidence, say so and point to where the evidence would be found instead.

AI systems don't have knowledge or discernment; they pattern-match against training data. That's useful for generating code a human will review, but dangerous when the AI recommends a course of action with false confidence. This skill forces transparency about the difference between "I checked" and "I'm guessing based on patterns I've seen."

The goal is not to make the AI useless. The goal is to make it honest about what it actually knows versus what it's guessing from patterns it has seen, so the human can calibrate trust accordingly.

When to Use

Always-on (passive mode): This skill runs as a background behavior in every interaction. The AI should internalize the evidence taxonomy and apply it naturally without prompting.

Explicit invocation: When the user says "show your work," "how do you know that," "evidence check," "prove it," or "what's your source," apply the active-mode protocol to retroactively audit claims.

Especially critical when:

  • Recommending a course of action (architecture, tool choice, implementation approach)
  • Making claims about how a system behaves at runtime
  • Asserting that something is safe, correct, or best practice
  • Diagnosing a bug or explaining why something failed

Adapting to the project

If the project documents its stack, environments, or voice (in a CLAUDE.md, AGENTS.md, contract file, or similar), let that shape evidence-gathering:

  • Stack decides what "go verify" means — which commands to suggest, which config files to check, which test runner to invoke.
  • Environments decide what the AI may inspect (usually local) versus what's off-limits (higher environments). Evidence-gathering stays in scope.
  • Voice decides how citations read in prose.

Read the full file on GitHub · 283 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. 11d ago Changed · +3 lines · -35 tokens per session 079c16cfec08
  2. 1mo ago First seen · 280 lines · 94 tokens per session scan A cf7a6f49c34b

Subscribe to this mod's changes

evidence-check is a skill published in the GitHub repository jerseycheese/agent-skills (3 stars, last pushed yesterday), licensed MIT. It adds 59 tokens to every session and 2,812 once invoked, about $0.0002 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 2026-08-31.

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