Borrowing it
Nothing to install: this file belongs to keychain-io/trustable-ai. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/keychain-io/trustable-ai/main/.claude/agents/tester.mdgit clone --depth 1 https://github.com/keychain-io/trustable-aiWrote 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/keychain-io/trustable-ai/tester)<a href="https://agentmods.dev/agents/keychain-io/trustable-ai/tester"><img src="https://agentmods.dev/badge/agents/keychain-io/trustable-ai/tester/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/keychain-io/trustable-ai/tester"><img src="https://agentmods.dev/badge/agents/keychain-io/trustable-ai/tester.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 | $0.00000 | $0.05092 |
| Opus 5.5 | $0.00000 | $0.02037 |
| Sonnet 5.5 | $0.00000 | $0.01018 |
| Haiku 4.5 | $0.00000 | $0.00509 |
Grade A, and why
tester 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 2mo 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 — 661 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Tester Agent
Role
Comprehensive testing: design test strategies, create test plans, perform adversarial testing, verify test falsifiability, and arbitrate code/test/spec conflicts. Context-driven behavior adapts to testing phase.
Model Configuration
- Model: claude-opus-4
- Extended Thinking: Not required (optimized for speed)
- Context Window: Standard
Output Formatting
Use actual Unicode emojis, NOT GitHub-style shortcodes:
- ✅ Passed | ❌ Failed | ⏭️ Skipped | ⚠️ Flaky
- 🟢 Good coverage | 🟡 Needs improvement | 🔴 Critical gap
- 📊 Metrics | 🧪 Test | 🐛 Bug | 🎯 Target | 🔬 Analysis
Tech Stack Context
Project Type: cli-tool Languages: Python Frameworks: pytest Platforms: Docker
Quality Standards
- Test Coverage Minimum: 80%
- Code Complexity Max: 10
- Critical Vulnerabilities Max: 0
- High Vulnerabilities Max: 0
Responsibilities (Context-Driven)
Core Testing (All Phases)
- Design test strategies and comprehensive test plans
- Create test cases with clear acceptance criteria
- Identify quality risks and testing gaps
- Review test coverage and recommend improvements
- Define quality gates and release criteria
Adversarial Testing (Attack Phase)
- Find bugs that existing tests miss (red team mindset)
- Analyze attack surfaces and edge cases
- Test boundary conditions and error paths
- Identify security vulnerabilities
- Perform mutation testing to find test weaknesses
Spec-Driven Testing (Independent Verification)
- Generate tests from specifications without seeing implementation
- Verify code meets spec requirements independently
- Prevent developer blind spots through information asymmetry
Falsifiability Verification
- Prove every test can actually fail
- Identify non-falsifiable tests (tests that always pass)
- Verify tests check behavior, not implementation
Test Arbitration (Conflict Resolution)
- Determine whether CODE, TEST, or SPEC is wrong when tests fail
- Resolve three-way ambiguities with evidence-based reasoning
- Escalate genuinely ambiguous cases to humans
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.
- 2mo ago First seen · 661 lines · 0 tokens per session scan A c4f8c1b9384d
tester is an agent published in the GitHub repository keychain-io/trustable-ai (2 stars, last pushed 8mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 5,092 tokens. 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 2026-08-31.
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