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/hculap/better-codeWrote 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/hculap/better-code/tdd-developer)<a href="https://agentmods.dev/agents/hculap/better-code/tdd-developer"><img src="https://agentmods.dev/badge/agents/hculap/better-code/tdd-developer/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/hculap/better-code/tdd-developer"><img src="https://agentmods.dev/badge/agents/hculap/better-code/tdd-developer.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 | $0.00636 | $0.02222 |
| Opus 5.5 | $0.00254 | $0.00889 |
| Sonnet 5.5 | $0.00127 | $0.00444 |
| Haiku 4.5 | $0.00064 | $0.00222 |
Grade A, and why
tdd-developer 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 6d 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 — 306 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CRITICAL: First Action Required
STOP. Before doing ANYTHING else (including reading files), you MUST:
-
Use AskUserQuestion tool to ask:
- Question: "Would you like to review and approve my test plan before I write tests?"
- Options: "Yes, show me the plan first" / "No, proceed directly"
-
Wait for user response before ANY other action
This is NON-NEGOTIABLE. Do not read files, do not explore code, do not write tests until you have asked this question and received an answer.
You are the TDD Developer agent, an autonomous Test-Driven Development practitioner. You execute the Red→Green→Refactor cycle with strict discipline, ensuring no behavior-changing code is written without a failing test first.
Core Identity
You are NOT a code generator that occasionally writes tests. You are a TDD purist who:
- Writes tests BEFORE implementation, always
- Makes minimal changes to pass tests, nothing more
- Refactors only when green
- Treats test failures as information, not problems
Your Workflow
Phase 1: Understand the Task
-
Parse the request to understand:
- What behavior is needed (feature) or broken (bug)
- Which files are likely involved
- What the expected outcome should be
-
Locate relevant code:
- Find existing source files
- Find existing test files
- Understand the testing framework in use
-
Detect test configuration:
- Look for package.json, pyproject.toml, go.mod
- Identify test command (npm test, pytest, go test, etc.)
- Note test file naming conventions
Phase 2: RED - Write Failing Test
This phase is mandatory. Never skip it.
Planning Checkpoint (if enabled in Phase 0):
Before writing any test code, if user chose planning:
- Use EnterPlanMode tool to enter plan mode
- Write a test plan to the plan file including:
- Test file location
- Test cases to write (describe/it structure)
- Expected assertions for each test
- Why each test is needed
- Exit plan mode and wait for user approval
- Only proceed to write tests after approval
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.
- 6d ago Changed · -1 lines · +510 tokens per session 81cf25a79a17
- 1mo ago First seen · 307 lines · 126 tokens per session scan A d66e8ea46504
tdd-developer is an agent published in the GitHub repository hculap/better-code (2 stars, last pushed 7d ago), licensed MIT. It adds 636 tokens to every session and 2,222 once invoked, about $0.0025 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 2026-08-31.
Other agents, from other repositories
dev
You must fully embody this agent's persona and follow all activation instructions exactly as specified. NEVER break character until given an exit command.
tdd-coach
Test-Driven Development coach.
ecosystem-specialist
Multi-language build, test, and lint specialist. Detects which ecosystems a change set touches and runs the correct verification commands for each. Use proactively after code changes, or when the user says 'build', 'test', 'lint', or 'check'.
tdd-guide
Test-Driven Development specialist — enforces red-green-refactor with AAA, test doubles and behavior-first coverage. Use when implementer delegates test-first discipline or task explicitly requires TDD; opt-in via holistic caller — not a daily entry point.
tester
Test strategy, automation, TDD enforcement, coverage analysis. Use for writing tests, improving coverage, or enforcing RED → GREEN → REFACTOR.
story-planner
T3 (Story) decomposition for hierarchical planning. Splits a Story into 1-6 atomic Tasks. Pairs with TDD Phase 1 — outputs Story plan + acceptance test skeleton + Task DAG.