tdd

A command for test-driven development, or TDD: write a test that fails, add the smallest implementation that makes it pass, then improve the code. It uses a dedicated guide agent and checks the narrow test before broader tests.

In plain words
What is it for?
Use it to implement a behavior or bug fix by defining the expected result, adding a failing regression test, making it pass, and reporting the tests and files changed.
Why use it?
Writing the expected behavior first gives the change a clear contract and helps prevent regressions. Keeping the implementation minimal also keeps the work focused.

Command

Install

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.

agentmods
npx agentmods add commands/cloudnative-co/claude-code-starter-kit/tdd
Clone the repo
git clone --depth 1 https://github.com/cloudnative-co/claude-code-starter-kit
Per session 13 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 152 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00013 $0.00152
Opus 5 $0.00006 $0.00076
Sonnet 5 $0.00003 $0.00030
Haiku 4.5 $0.00001 $0.00015

Measured 2d ago against content hash f497708d2340, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

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.

commands/tdd.md · 27 lines

What it actually says

/tdd

Request: $ARGUMENTS

Use the tdd-guide agent for the workflow. Keep the session focused on the requested behavior.

Steps

  1. Define the expected behavior or bug regression in one sentence.
  2. Add the smallest failing test that proves the contract.
  3. Implement the minimum code needed to pass.
  4. Refactor only after the test is green.
  5. Run the narrow test first, then broader relevant checks.

Output

  • Behavior covered
  • Tests added or changed
  • Implementation files changed
  • Commands run and results
  • Remaining gaps or risks
Changes

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.

  1. 2d ago First seen · 27 lines · 13 tokens per session scan A f497708d2340

Subscribe to this mod's changes

tdd is a command published in the GitHub repository cloudnative-co/claude-code-starter-kit (147 stars, last pushed 8d ago), licensed MIT. It adds 13 tokens to every session and 152 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 2026-08-30.