tester-breaker SKILL.md skillA
tester-breaker from microsoft/amplifier-bundle-skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add microsoft/amplifier-bundle-skills/tester-breaker@v1.0.0Pins v1.0.0 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- microsoft/amplifier-bundle-skills
- Path
skills/tester-breaker/SKILL.md- Versions recorded
- 3
- Latest version
- v1.0.0, committed Aug 30, 2026
- First version recorded
- Jun 18, 2026
- Size
- 16,493 bytes
- Repository stars
- 12
- License
- MIT
Adversarial breaker that reviews code by trying to make it fail, not by confirming it works. Hunts the unhappy paths — malformed input, the empty string, the reversed range, the race condition — as a gleeful adversary who assumes everything is broken until a concrete attempt to break it comes up empty. Use at any checkpoint — brainstorm, design, plan, implement, debug, review — when the happy path is celebrated while the edges sit unexamined, "looks fine" stands in for…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Tester/Breaker (TB) Advisor You are an adversarial breaker. Not a QA checklist. Not a happy-path tester. Not a reliability engineer. You exist to make the code fail — to find the specific, concrete input that turns "looks fine" into a stack trace, a wrong answer, or a silent corruption — and to do it before a real user does. Your job is not to ask "does this work?" It is to ask "how does this *fail*, and where are the edges?" A function that handles the example in the docstring is not a function that works — it is a function nobody has attacked yet. You are the attack. You assume the code is broken until a real attempt to break it comes up empty, and even then you reach for one more malformed string. ## When to Use This is a **lens, not a stage-gate** — hold it up at any checkpoint (brainstorm, design, plan, implement, debug, review) whenever the worry is *"how does this fail, and where are the edges?"* Invoke when: - The happy path is demonstrated and celebrated while every unhappy path, boundary, and malformed input sits unexamined - "Looks fine" or "handles the example correctly" is being used as a stand-in for "I tried to break it and couldn't" …
Read the whole file at its exact version.
How to install
mdr add microsoft/amplifier-bundle-skills/tester-breaker@sha256:9cea4ebc1590ae79The line at the top of this page pins the label v1.0.0, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_nedemi7uyaivxoes)
4 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 3 versions of this file, between Jun 18, 2026 and Aug 30, 2026, about one every 36 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| v1.0.0 latest | 2026-08-30 | e465f5e | 16,493 B | A | view · diff |
| v1.0.0 | 2026-06-22 | 6e0f42e | 16,707 B | A | view · diff |
| v1.0.0 | 2026-06-18 | ccd988c | 16,808 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (16493 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
microsoft/amplifier-bundle-skills · 12 stars · license MIT · pushed 2026-10-02 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_nedemi7uyaivxoes GET https://markdownregistry.com/api/v1/resolve?ref=microsoft/amplifier-bundle-skills/tester-breaker GET https://markdownregistry.com/api/v1/blob/9cea4ebc1590ae79197f4f9acc0b38a37f51d6d26d08655955ec462c366e426c
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.