build-writer-tdd

build-writer-tdd is an agent for Claude Code from Automattic/radical-pipelines. It costs 33 tokens per session (1,283 once invoked), scanned A, original, GPL-3.0.

A build-plan task executor that uses test-driven development, or TDD: writing tests for the desired behavior before implementing the code.

In plain words
What is it for?
Use it to complete one planned task when unit tests and TDD are appropriate.
Why use it?
It ties the implementation to the task's acceptance criteria and produces tests alongside the code.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the radical-pipelines plugin — 1 skill, 18 agents shipped together

Good fit Use it to complete one planned task when unit tests and TDD are appropriate.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/automattic/radical-pipelines/build-writer-tdd
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.

Clone the repo
git clone --depth 1 https://github.com/Automattic/radical-pipelines

Made for: Claude Code.

Or install radical-pipelines, the plugin that ships this one along with the rest of its 1 skill, 18 agents.

Wrote 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.

agentmods badge for build-writer-tdd

README.md
[![agentmods](https://agentmods.dev/badge/agents/automattic/radical-pipelines/build-writer-tdd/github.svg)](https://agentmods.dev/agents/automattic/radical-pipelines/build-writer-tdd)
Your own site
<a href="https://agentmods.dev/agents/automattic/radical-pipelines/build-writer-tdd"><img src="https://agentmods.dev/badge/agents/automattic/radical-pipelines/build-writer-tdd/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.

agentmods 80×15 button for build-writer-tdd

Your own site · 80×15
<a href="https://agentmods.dev/agents/automattic/radical-pipelines/build-writer-tdd"><img src="https://agentmods.dev/badge/agents/automattic/radical-pipelines/build-writer-tdd.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 33 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,283 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 5.1 $0.00033 $0.01283
Opus 5 $0.00016 $0.00642
Sonnet 5 $0.00007 $0.00257
Haiku 4.5 $0.00003 $0.00128

Measured 10d ago against content hash d337556f6611, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

build-writer-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 10d 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.

agents/build-writer-tdd.md · 65 lines

The source is not reproduced here

Licensed GPL-3.0

The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

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. 10d ago First seen · 65 lines · 33 tokens per session scan A d337556f6611

Subscribe to this mod's changes

build-writer-tdd is an agent published in the GitHub repository Automattic/radical-pipelines (11 stars, last pushed yesterday), licensed GPL-3.0. It adds 33 tokens to every session and 1,283 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 2026-08-30.

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