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 skills add JansenAnalytics/claudex --skill test-criticgit clone --depth 1 https://github.com/JansenAnalytics/claudexWrote 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/skills/jansenanalytics/claudex/test-critic)<a href="https://agentmods.dev/skills/jansenanalytics/claudex/test-critic"><img src="https://agentmods.dev/badge/skills/jansenanalytics/claudex/test-critic.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 5.1 | $0.00048 | $0.00748 |
| Opus 5 | $0.00024 | $0.00374 |
| Sonnet 5 | $0.00010 | $0.00150 |
| Haiku 4.5 | $0.00005 | $0.00075 |
Grade A, and why
test-critic 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 — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.
test-critic
Evaluates test quality — not just "do tests pass" but "do tests actually catch bugs?"
Quick Start
# Full audit
test-critic /path/to/project --full
# Quick (coverage only, no mutations)
test-critic /path/to/project --quick
# Individual scripts
node ${CLAUDE_SKILLS_DIR:-$HOME/.claude-agent/.claude/skills}/test-critic/scripts/coverage.cjs /path/to/project
node ${CLAUDE_SKILLS_DIR:-$HOME/.claude-agent/.claude/skills}/test-critic/scripts/gaps.cjs /path/to/project
node ${CLAUDE_SKILLS_DIR:-$HOME/.claude-agent/.claude/skills}/test-critic/scripts/quality.cjs /path/to/project
node ${CLAUDE_SKILLS_DIR:-$HOME/.claude-agent/.claude/skills}/test-critic/scripts/mutate.cjs /path/to/project --limit 50
node ${CLAUDE_SKILLS_DIR:-$HOME/.claude-agent/.claude/skills}/test-critic/scripts/report.cjs /path/to/project
Options
| Flag | Description |
|---|---|
--quick |
Coverage + gaps + quality only (no mutations) |
--full |
Everything including mutation testing |
--framework jest|vitest|pytest|auto |
Test framework (default: auto-detect) |
--mutate-limit N |
Max mutations to try (default: 100) |
--output-dir DIR |
Where to write reports |
--format md|json|both |
Report format |
Components
- coverage.cjs — Runs tests with coverage, identifies untested files, happy-path-only files, critical files with low coverage
- mutate.cjs — Lightweight mutation testing: modifies source code and checks if tests catch the change
- gaps.cjs — Static analysis to find untested error handlers, null checks, boundary conditions, division-by-zero
- quality.cjs — Analyzes test code itself: missing assertions, poor names, excessive mocking, hardcoded sleeps
- review.cjs — Orchestrator that runs all components and generates final report
- report.cjs — Combines all results into scored report with prioritized test suggestions
Output
coverage-analysis.json— Coverage breakdowntest-gaps.json— Identified test gaps with suggestionstest-quality.json— Test code quality issuesmutation-results.json— Mutation testing resultstest-critic-report.json— Combined report with health scoretest-critic-report.md— Human-readable markdown report
What ships with it
6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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 · 76 lines · 48 tokens per session scan A 8647ea367e65
test-critic is a skill published in the GitHub repository JansenAnalytics/claudex (5 stars, last pushed 2mo ago), licensed MIT. It adds 48 tokens to every session and 748 once invoked, about $0.0002 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 2026-09-03.
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