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.
npx skills add bostonaholic/team --skill test-first-developmentgit clone --depth 1 https://github.com/bostonaholic/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/bostonaholic/team/test-first-development)<a href="https://agentmods.dev/skills/bostonaholic/team/test-first-development"><img src="https://agentmods.dev/badge/skills/bostonaholic/team/test-first-development.svg" alt="Measured on agentmods" 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 | $0.00024 | $0.00442 |
| Opus 5 | $0.00012 | $0.00221 |
| Sonnet 5 | $0.00005 | $0.00088 |
| Haiku 4.5 | $0.00002 | $0.00044 |
Grade A, and why
test-first-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 3d 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
Test-First Development
Acceptance tests are the immutable scope fence (principle-scope-fence). Read
references/procedure.md for complete error handling,
stub limits, and the acceptance-versus-step-level distinction.
Core Rule
Write ALL acceptance tests from the plan BEFORE any implementation code. Use the plan's exact names; add, omit, or rename none. If boundary, invalid-input, failure, concurrency, auth, or resource-limit cases are missing, return to PLAN.
1. Write every planned test
Tests assert observable outcomes and follow skills/test-style/SKILL.md.
Audit each against that skill's named checklist before reporting results.
2. Make Sure That Tests Fail Correctly
Run the full suite. Every new test must FAIL through its assertion, never ERROR;
every existing test must pass. This is a deterministic gate
(principle-mechanical-gates). Then run the project's static checks, including
typecheck, and make them pass. Report both results.
3. Fix errors, not failures
For missing imports, fixtures, types, or runner config, add only the minimum placeholder module, fixture, type stub, or configuration required to execute. Stubs remain visibly incomplete. Never add implementation to make a test run.
4. Lock the test list
After correct Red state, acceptance tests are immutable during IMPLEMENT:
- add none;
- remove none;
- change no assertions;
- rename none.
A needed change returns to PLAN; the structure regenerates the plan. There is no approval step.
Two test levels
- Feature acceptance: immutable, coarse observable behavior; defines what.
- Step-level TDD: Red, Green, Refactor unit tests; freely changed during implementation; helps build how.
Completion Contract
Proceed to VERIFY only when all acceptance tests pass unchanged, none were added or removed, and the full prior suite has no regression.
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 3d ago Changed · -78 lines · -5 tokens per session d536b4d6ab74
- 4d ago First seen · 137 lines · 29 tokens per session scan A 458f5c13b7f0
test-first-development is a skill published in the GitHub repository bostonaholic/team (11 stars, last pushed today), licensed MIT. It adds 24 tokens to every session and 442 once invoked, about $0.0001 per session on Opus 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.
Other skills, from other repositories
behavior-contract
Bug condition/postcondition formalization as testable Behavior Contracts. Defines invariants that must be preserved across fixes.
strict-tdd
Strict RED->GREEN->REFACTOR test-driven development with enforcement. Never write production code before a failing test. Atomic commits per TDD cycle.
test-driven-development
Strict RED-GREEN-REFACTOR cycle enforcement. Tests are never skipped or deferred. Run mode only, never watch mode. Exit code evidence mandatory.
tdd-enforcement
Red-Green-Refactor TDD methodology with mandatory failing tests, minimal implementation, quality refactoring, and 80% coverage gating.
orchestrated-execution
Execute work units through the rigorous 4-phase Metaswarm cycle (Implement -> Validate -> Adversarial Review -> Commit) with independent quality gate enforcement.
writing-plans
Use when you have a spec or requirements for a multi-step task, before touching code. Creates bite-sized TDD implementation plans with dependency tracking.