proof

proof is an agent for Claude Code from jeremylongshore/tons-of-skills-marketplace. It costs 84 tokens per session (2,907 once invoked), scanned A, original, MIT.

A software-testing specialist that identifies risky parts of an application and writes tests for them. It covers integration tests, which check multiple parts working together, and Playwright end-to-end tests, which simulate complete user journeys in a browser.

In plain words
What is it for?
Use it to add tests where coverage is missing, test critical user flows, investigate flaky tests, and enforce test checks in CI.
Why use it?
It helps find failures in important paths, reduce flaky tests that developers stop trusting, and prevent slow CI from becoming a daily cost.

Agent for Claude Code

Written for Claude Code: background in frontmatter. Also seen: model in frontmatter; built for gstack.

Part of the tonone plugin — 100 agents, 9 plugins shipped together

Good fit Use it to add tests where coverage is missing, test critical user flows, investigate flaky tests, and enforce test checks in CI.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/jeremylongshore/tons-of-skills-marketplace/proof
About the project

Tons of Skills is a model-agnostic marketplace that distributes reusable skills, plugins, agents, commands, hooks, and settings for coding-agent tools. It is intended for people who want to browse, install, and manage agent extensions, with Claude Code as its verified native harness. The catalogue entries are extensions provided by or associated with this marketplace.

jeremylongshore/tons-of-skills-marketplace · 2,717 stars · on GitHub · tonsofskills.com

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/jeremylongshore/tons-of-skills-marketplace

Made for: Claude Code.

Or install tonone, the plugin that ships this one along with the rest of its 100 agents, 9 plugins.

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 proof

README.md
[![agentmods](https://agentmods.dev/badge/agents/jeremylongshore/tons-of-skills-marketplace/proof/github.svg)](https://agentmods.dev/agents/jeremylongshore/tons-of-skills-marketplace/proof)
Your own site
<a href="https://agentmods.dev/agents/jeremylongshore/tons-of-skills-marketplace/proof"><img src="https://agentmods.dev/badge/agents/jeremylongshore/tons-of-skills-marketplace/proof/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 proof

Your own site · 80×15
<a href="https://agentmods.dev/agents/jeremylongshore/tons-of-skills-marketplace/proof"><img src="https://agentmods.dev/badge/agents/jeremylongshore/tons-of-skills-marketplace/proof.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 84 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,907 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 $0.00084 $0.02907
Opus 5 $0.00042 $0.01453
Sonnet 5 $0.00017 $0.00581
Haiku 4.5 $0.00008 $0.00291

Measured 8d ago against content hash 8f3e38260891, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

proof 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 8d 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/ai-agency/tonone/agents/proof.md · 230 lines

How it starts

The opening of the file, as written. The whole thing — 230 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are Proof — QA and testing engineer on Engineering Team. Write tests. Don't produce testing strategy PowerPoints or advise teams on what they should do. Assess risk, pick test type, write code, ship it.

Think like founder with reliability problem: what is smallest test surface that gives highest confidence? Flaky test suite developers ignore is worse than no test suite. Slow CI pipeline is tax on every developer's day.

Communication

Respond terse. All technical substance stays — only filler dies. Follow output-kit protocol: compressed prose, no filler, fragments OK. Code/security/commits: normal English. See docs/output-kit.md for CLI skeleton, severity indicators, 40-line rule.

Operating Principle

Test risk, not lines.

Coverage is means, not goal. 90% coverage with green tests on getters and framework glue is worse than 60% coverage exercising every path money flows through. Before writing single test, ask: What breaks here? What's blast radius? Who notices first?

Risk = likelihood × impact. High-likelihood + high-impact paths get tested first, deeply, at right layer. Low-risk paths get skipped or covered by single smoke test. Call this out explicitly — "we're not testing X because risk is low and maintenance cost is high."

If testing strategy is unclear, surface risk map before writing any code — not after.

Scope

Owns: test strategy, E2E test suites (Playwright, Cypress), integration testing, API testing, load/performance testing, test infrastructure (CI runners, parallelization, sharding), test data management, flaky test triage, coverage analysis, contract testing Also covers: test environment management, snapshot testing, test reporting, test fixtures and factories, mocking strategies, visual design QA (red flags, severity classification) Does not own: unit tests within specialist's domain (each agent owns their own unit tests), security testing (Warden), CI/CD pipeline config (Relay — but you define what tests run where)

Read the full file on GitHub · 230 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. 8d ago First seen · 230 lines · 84 tokens per session scan A 8f3e38260891

Subscribe to this mod's changes

proof is an agent published in the GitHub repository jeremylongshore/tons-of-skills-marketplace (2,717 stars, last pushed today), licensed MIT. It adds 84 tokens to every session and 2,907 once invoked, about $0.0004 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.