Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add bdfinst/agentic-dev-team/plugin install dev-teamWrote 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/skills/bdfinst/agentic-dev-team/test-driven-development)<a href="https://agentmods.dev/skills/bdfinst/agentic-dev-team/test-driven-development"><img src="https://agentmods.dev/badge/skills/bdfinst/agentic-dev-team/test-driven-development/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/skills/bdfinst/agentic-dev-team/test-driven-development"><img src="https://agentmods.dev/badge/skills/bdfinst/agentic-dev-team/test-driven-development.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 2 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Anti-Refusal · line 122 Skill instructs the agent to omit warnings, disclaimers, or ethical commentary. Stripping safety caveats hides risk from the user and is a common jailbreak preamble.Fix: Remove instructions that suppress warnings, disclaimers, or ethical commentary. Let the agent surface safety-relevant caveats to the user.
- medium Agent Snooping · line 16 Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
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 | $0.00099 | $0.02339 |
| Opus 5.5 | $0.00040 | $0.00936 |
| Sonnet 5.5 | $0.00020 | $0.00468 |
| Haiku 4.5 | $0.00010 | $0.00234 |
Grade A, and why
test-driven-development 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 — 170 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test-Driven Development
Overview
Enforces strict RED-GREEN-REFACTOR discipline with verifiable gates. LLMs are especially prone to skipping tests or writing them after implementation — this skill exists because that tendency produces code that looks tested but isn't actually validated.
Positioning: this is an advisory methodology reference, not a build cadence. /build runs a single cadence — Code-First Small Batches: implement one behavior, write its test in the same cycle, refactor on every green (docs/experiments/RECOMMENDATIONS.md Rec 3: test-first ordering by itself buys nothing; the per-green refactoring is the mechanism, and it is mandatory). /build never dispatches into this skill automatically. Use it only when a human explicitly asks for test-first discipline outside of /build, or when auditing existing code for TDD discipline after the fact. When applied, every rule below still holds — including the Iron Law and its hard gates.
Defect fixes are not covered by this advisory status. General feature development under /build uses Code-First Small Batches and never requires the full RED-GREEN-REFACTOR cycle in this skill. Fixing a bug is different and is mandatory, not optional: always reproduce the defect with a failing test before writing the fix. That hard gate lives in skills/systematic-debugging/SKILL.md Phase 4, not here — this skill remains advisory-only for new-feature construction.
Iron Law
No production code without a failing test first. If you didn't watch the test fail, you don't know if it tests the right thing. Code written before tests must be deleted and reimplemented from the test — no exceptions.
Constraints
- Do not write implementation code without a failing test first
- Do not move to the next unit of work until all tests pass
- Do not skip the refactor step — it's where design quality happens
- Do not rationalize exceptions to the cycle (see Rationalization Prevention below)
- Before doubling any collaborator, check it against
${CLAUDE_PLUGIN_ROOT}/knowledge/internal-collaborator-doubling.md#the-three-blockers-exhaustive's blocker table
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 0861547143eb
- 1mo ago First seen · 170 lines · 99 tokens per session scan A f07a5ec2a96f
test-driven-development is a skill published in the GitHub repository bdfinst/agentic-dev-team (295 stars, last pushed 4d ago), licensed MIT. It adds 99 tokens to every session and 2,339 once invoked, about $0.0004 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 2026-09-03.
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principle-test-behavior-not-implementation
Apply when you write, change, or keep a test. Assert what the code's users can observe, so that the test fails when that behavior breaks and keeps passing when only the internals change.
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python
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tdd
This skill should be used when the user wants to implement features or fix bugs using test-driven development. Enforces the RED-GREEN-REFACTOR cycle with vertical slicing, context isolation between test writing and implementation, human checkpoints, and auto-test feedback loops. Uses multi-agent orchestration with the…