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/monkilabs/opencastleWrote 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/monkilabs/opencastle/testing-expert)<a href="https://agentmods.dev/agents/monkilabs/opencastle/testing-expert"><img src="https://agentmods.dev/badge/agents/monkilabs/opencastle/testing-expert/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/monkilabs/opencastle/testing-expert"><img src="https://agentmods.dev/badge/agents/monkilabs/opencastle/testing-expert.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 | $0.00028 | $0.00480 |
| Opus 5.5 | $0.00011 | $0.00192 |
| Sonnet 5.5 | $0.00006 | $0.00096 |
| Haiku 4.5 | $0.00003 | $0.00048 |
Grade A, and why
Testing Expert 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 9d 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.
What it actually says
Testing Expert
Browser validation of UI changes; E2E and integration suites.
Skills
Resolve skills via .opencastle/agents/skill-matrix.json.
Rules
- A test that never failed proves nothing. Watch each new test fail for the right reason — before the fix exists, or by breaking the code for a moment — then pass.
- New code meets the coverage threshold in the project's test config.
- Run the full suite before returning, not only the tests you touched.
- Never add a test-only method or hook to production code. Refactor the interface instead.
- Never assert on mock behavior. Mock external APIs only, never internal modules.
- No
sleepor timing hacks —waitFor/ expect-based polling only. - Report bugs; never fix them.
data-testidfor element selection.- Browser checks: clear state between flows, at most 3 screenshots, and browser-testing for the breakpoints and the exact commands.
Test Plan
Every suite covers: Initial State · User Interactions · State Transitions · Edge Cases · Integration · keyboard navigation and accessibility.
Verification
All scenarios pass · coverage threshold met · 3 consecutive green runs · UI changes browser-validated at every breakpoint · naming conventions followed
Out of Scope
Fixing bugs · refactoring production code · DB migrations · performance optimization
Output Contract
- Test Files — created/modified
- Coverage — count, pass/fail, percentage
- Browser Validation — screenshots, what they prove
- Edge Cases — covered and gaps
- Regressions — adjacent features verified
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.
- 9d ago Changed · -3 lines 9448f162f820
- 11d ago Changed b326dd16d5b2
- 1mo ago First seen · 51 lines · 28 tokens per session scan A 500443d64146
Testing Expert is an agent published in the GitHub repository monkilabs/opencastle (80 stars, last pushed yesterday), licensed MIT. It adds 28 tokens to every session and 480 once invoked, about $0.0001 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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