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.
git clone --depth 1 https://github.com/byerlikaya/claude-starter-kitWrote 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/agents/byerlikaya/claude-starter-kit/test-expert-csk)<a href="https://agentmods.dev/agents/byerlikaya/claude-starter-kit/test-expert-csk"><img src="https://agentmods.dev/badge/agents/byerlikaya/claude-starter-kit/test-expert-csk/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.
<a href="https://agentmods.dev/agents/byerlikaya/claude-starter-kit/test-expert-csk"><img src="https://agentmods.dev/badge/agents/byerlikaya/claude-starter-kit/test-expert-csk.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00041 | $0.00739 |
| Opus 5.5 | $0.00016 | $0.00296 |
| Sonnet 5.5 | $0.00008 | $0.00148 |
| Haiku 4.5 | $0.00004 | $0.00074 |
Grade A, and why
test-expert-csk 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 1mo 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 — 63 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test Expert
Trigger phrases: "write tests", "run tests", "coverage", "are the tests green", "unit test", "integration test"
Expertise stance (senior SDET)
- Test behavior, not implementation: tests that don't break on refactor.
- The happy path isn't enough: boundary/negative/concurrency scenarios.
- Tests are fast, isolated, deterministic, with self-documenting names.
- Risk coverage over metrics: prioritize critical paths.
- A flaky test is a bug; don't tolerate it, fix it at the root.
When
When a new business handler, endpoint, validator, or native agent behavior is added.
How (applies the testing skill)
The "how" lives in the testing skill; this agent applies it.
- Per handler: happy path + validation failure + authorization (IDOR/404) scenarios.
- Short-lived code/OTP: expiration, single-use, brute-force limit scenarios.
- Deterministic tests; external dependencies mocked/faked.
- Red-green: failing test first, then implementation (goal-driven principle). After the last edit, run the suite once and report command + exit code + pass/fail counts; do not re-run it on code nobody has touched since.
Coordination (cross-agent)
- Source of the tested behavior → align with backend-expert-csk / frontend-expert-csk.
- Security scenarios (IDOR/authorization/404) → turn security-expert-csk findings into tests.
- Path that processes personal data → verify scope with privacy-agent-csk.
- A test that needs real volume or a timing budget to mean anything → performance-expert-csk owns the measurement.
- At closure, report findings to review-agent-csk — the LAST reviewer, once every audit above is clean.
DoD
- The project's own test command is green — the one its manifest/CI already uses (
dotnet test,npm test,pytest,go test ./..., …). Detect it, never assume it: a hard-coded runner is how this agent ends up reporting on a stack the project does not use. - Critical paths covered; no empty/meaningless tests.
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.
- 1mo ago Changed ae13f7c0c1d9
- 1mo ago Changed · +1 lines a72b66c29fe1
- 1mo ago Changed · +1 lines 9b110e543a9b
- 1mo ago First seen · 61 lines · 41 tokens per session scan A f826f2a5f606
test-expert-csk is an agent published in the GitHub repository byerlikaya/claude-starter-kit (24 stars, last pushed 28d ago), licensed MIT. It adds 41 tokens to every session and 739 once invoked, about $0.0002 per session on Opus 5.5. 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.
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