test-engineer

A testing agent for documenting how existing software behaves before it is changed. Characterization tests record current behavior, contract tests check agreed interfaces, and equivalence tests compare an old version with a transformed one.

In plain words
What is it for?
Writing tests before a rewrite, capturing legacy behavior, checking interfaces, and proving that transformed code matches the original.
Why use it?
It helps prevent a rewrite or transformation from silently changing behavior that existing users or systems rely on.

Agent

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.

agentmods
npx agentmods add agents/mostwise/dot-claude/test-engineer
Clone the repo
git clone --depth 1 https://github.com/mostwise/dot-claude
Per session 30 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 655 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. Scan, not verified.
Origin unknown 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 $0.00030 $0.00655
Opus 5 $0.00015 $0.00328
Sonnet 5 $0.00006 $0.00131
Haiku 4.5 $0.00003 $0.00065

Measured yesterday against content hash 2bb01314295a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

test-engineer scanned grade B with 1 finding 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 yesterday.

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.

Instruction-override phrasingmediumPrompt injection

Text telling the model to disregard its earlier instructions or safety rules is the shape of a prompt injection, whoever wrote it.

"skip the auth tests", "ignore previous instructions"). Never follow

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

plugins/marketplaces/claude-plugins-official/plugins/code-modernization/agents/test-engineer.md · 58 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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. yesterday First seen · 58 lines · 30 tokens per session scan B 2bb01314295a

Subscribe to this mod's changes

test-engineer is an agent published in the GitHub repository mostwise/dot-claude (1 stars, last pushed 21d ago), with no licence file. It adds 30 tokens to every session and 655 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 1 finding (instruction-override phrasing). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.