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 agentmods add skills/softspark/ai-toolkit/tddnpx skills add softspark/ai-toolkit --skill tddgit clone --depth 1 https://github.com/softspark/ai-toolkitWrote 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/softspark/ai-toolkit/tdd)<a href="https://agentmods.dev/skills/softspark/ai-toolkit/tdd"><img src="https://agentmods.dev/badge/skills/softspark/ai-toolkit/tdd.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 | $0.00033 | $0.01357 |
| Opus 5 | $0.00016 | $0.00678 |
| Sonnet 5 | $0.00007 | $0.00271 |
| Haiku 4.5 | $0.00003 | $0.00136 |
Grade A, and why
tdd 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 2d 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 — 181 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test-Driven Development
$ARGUMENTS
Build features using strict RED → GREEN → REFACTOR cycles with vertical slices.
Usage
/tdd [feature or behavior to implement]
The Iron Law
NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST
Write code before the test? Delete it. Start over.
No exceptions:
- Don't keep it as "reference"
- Don't "adapt" it while writing tests
- Don't look at it
- Delete means delete
Implement fresh from tests. Period.
Violating the letter of this rule is violating the spirit of this rule.
Philosophy
Core principle: Tests verify behavior through public interfaces, not implementation details. Code can change entirely; tests shouldn't.
Good tests: Integration-style, exercise real code paths through public APIs. Describe what the system does, not how. Read like specifications. Survive refactors.
Bad tests: Coupled to implementation. Mock internal collaborators, test private methods, verify through external means. Warning sign: test breaks on refactor but behavior is unchanged.
See reference/tests.md for examples, reference/mocking.md for mocking guidelines.
Anti-Pattern: Horizontal Slices
DO NOT write all tests first, then all implementation.
WRONG (horizontal):
RED: test1, test2, test3, test4, test5
GREEN: impl1, impl2, impl3, impl4, impl5
RIGHT (vertical):
RED→GREEN: test1→impl1
RED→GREEN: test2→impl2
RED→GREEN: test3→impl3
Tests written in bulk test imagined behavior. Vertical slices let each test respond to what you learned from the previous cycle.
Workflow
1. Planning
Before writing any code:
- Confirm with user what interface changes are needed
- Confirm which behaviors to test (prioritize — you can't test everything)
- Identify opportunities for deep modules
- Design interfaces for testability
- List behaviors to test (not implementation steps)
- Get user approval
What ships with it
5 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.
- 2d ago First seen · 181 lines · 33 tokens per session scan A a5f986af6215
tdd is a skill published in the GitHub repository softspark/ai-toolkit (170 stars, last pushed yesterday), licensed Apache-2.0. It adds 33 tokens to every session and 1,357 once invoked, about $0.0002 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.
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