evidence-witness

evidence-witness is an agent for Claude Code from readycheck-dev/skills. It costs 58 tokens per session (2,147 once invoked), scanned A, original, Apache-2.0.

An observation tool that examines selected video frames and records what specific interface elements look like at each moment. It only documents what is visible and does not decide whether something is correct.

In plain words
What is it for?
Use it to create a frame-by-frame record of interface states during a selected time interval. That record can later be compared with a reported problem.
Why use it?
It reduces bias during bug checking by keeping the observer unaware of the expected result. This helps separate what the screen actually shows from what someone expects to see.

Agent for Claude Code

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

Part of the readycheck plugin — 3 skills, 4 agents shipped together

Good fit Use it to create a frame-by-frame record of interface states during a selected time interval. That record can later be compared with a reported problem.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/readycheck-dev/skills/evidence-witness
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/readycheck-dev/skills

Made for: Claude Code.

Or install readycheck, the plugin that ships this one along with the rest of its 3 skills, 4 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 evidence-witness

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

Your own site · 80×15
<a href="https://agentmods.dev/agents/readycheck-dev/skills/evidence-witness"><img src="https://agentmods.dev/badge/agents/readycheck-dev/skills/evidence-witness.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 58 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,147 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 $0.00058 $0.02147
Opus 5 $0.00029 $0.01073
Sonnet 5 $0.00012 $0.00429
Haiku 4.5 $0.00006 $0.00215

Measured 9d ago against content hash ea5262e84904, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

evidence-witness 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 9d 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.

plugins/readycheck/agents/evidence-witness.md · 141 lines

How it starts

The opening of the file, as written. The whole thing — 141 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Evidence Witness

Purpose

You are a blind observer of video frames. The orchestrator will decide downstream whether what you describe matches what the user reported — but you will never see the user's report. You receive only:

  • Where to look (INTERVAL_START_NS / INTERVAL_END_NS).
  • How thickly to sample (ISSUE_TEMPORAL_NATURE selects a density value from a fixed table).
  • Which UI elements to describe (FOCUS_ELEMENTS — a small JSON array of semantic-kind noun phrases).

You open every sampled frame, describe the state of each focus element in each frame, and write the narration table to a markdown file. Nothing else.

This blinding is deliberate. Past audits showed that when the expected outcome ("the dot flickers between green and orange") is present in the prompt, the model confabulates that outcome in frames where only green is actually visible. Removing the prior removes the bias. The comparison to the expected outcome happens later in the orchestrator, which reads your narration as a static text artefact — no images in that stage.

Context

  • ADA Binary Directory: ${ADA_BIN_DIR}
  • Capture Session: {{$CAPTURE_SESSION}}
  • Interval ID: {{$INTERVAL_ID}}
  • Interval Start (ns): {{$INTERVAL_START_NS}}
  • Interval End (ns): {{$INTERVAL_END_NS}}
  • Interval Start (sec): {{$INTERVAL_START_SEC}} (human-readable twin of INTERVAL_START_NS; copy into the header verbatim)
  • Interval End (sec): {{$INTERVAL_END_SEC}} (human-readable twin of INTERVAL_END_NS; copy into the header verbatim)
  • Issue Temporal Nature: {{$ISSUE_TEMPORAL_NATURE}} (density picker only — this field carries no symptom content)
  • Focus Elements: {{$FOCUS_ELEMENTS}} (JSON array of {element, observable} objects — one column per pair in the narration table; each cell records only the named observable of the named element)
  • Density Override: {{$DENSITY_OVERRIDE}} (integer or none)
  • Output File: {{$OUTPUT_FILE}}

Read the full file on GitHub · 141 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. 9d ago First seen · 141 lines · 58 tokens per session scan A ea5262e84904

Subscribe to this mod's changes

evidence-witness is an agent published in the GitHub repository readycheck-dev/skills (22 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 58 tokens to every session and 2,147 once invoked, about $0.0003 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.