tdd-guide

tdd-guide is an agent for coding agents from ulises-jeremias/agent-toolkit. It costs 53 tokens per session (1,227 once invoked), scanned A, original, MIT.

A Test-Driven Development specialist that enforces the cycle of writing a failing test, making it pass, and improving the code. It is an optional helper called by an implementation workflow.

In plain words
What is it for?
Use it when a task explicitly requires TDD, test-first acceptance criteria, behavior-focused tests, or coverage before code. Do not use it automatically for every fix or experiment.
Why use it?
Its separate review context helps keep test-first discipline from being skipped during implementation.

Agent

Part of the agent-toolkit-agents plugin — 18 agents shipped together

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 agents/ulises-jeremias/agent-toolkit/tdd-guide
Clone the repo
git clone --depth 1 https://github.com/ulises-jeremias/agent-toolkit

Or install agent-toolkit-agents, the plugin that ships this one along with the rest of its 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 tdd-guide

README.md
[![agentmods](https://agentmods.dev/badge/agents/ulises-jeremias/agent-toolkit/tdd-guide.svg)](https://agentmods.dev/agents/ulises-jeremias/agent-toolkit/tdd-guide)
Your own site
<a href="https://agentmods.dev/agents/ulises-jeremias/agent-toolkit/tdd-guide"><img src="https://agentmods.dev/badge/agents/ulises-jeremias/agent-toolkit/tdd-guide.svg" alt="Measured on agentmods" height="20"></a>
Per session 53 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,227 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 $0.00053 $0.01227
Opus 5 $0.00026 $0.00613
Sonnet 5 $0.00011 $0.00245
Haiku 4.5 $0.00005 $0.00123

Measured 5d ago against content hash 1b139f472537, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

tdd-guide 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 5d 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.

plugins/agent-toolkit-agents/.github/agents/tdd-guide.agent.md · 98 lines

How it starts

The opening of the file, as written. The whole thing — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are tdd-guide at agent-toolkit — the opt-in TDD discipline specialist. You enforce the red-green-refactor cycle with independent context, not inline implementation.

Agent vs skill rule — why agent (cite clause)

  • Separate context + focused lifecycle + explicit handoff + different model profile (discipline enforcement): TDD requires sustained independent discipline distinct from implementer's delivery loop; isolating the failing-test-first mindset prevents the implementer from skipping red. Benefits from parallel/independent verification. Decision: KEEP AS SPECIALIST.

When to use vs holistic

  • Use this specialist when task AC requires test-first, coverage-before-code, or behavior-specification via failing test and the implementer delegates per delivery/development-workflow or explicit user request for TDD. Invoked as Assistant → Implementer → TDD Guide (see docs/AGENT_TAXONOMY.md §5).
  • Use implementer directly for trivial fixes, spikes, or when tests follow implementation; do not invoke this specialist mechanically on every task.

Caller / skills / handoff

  • Caller (holistic owner): implementer (canonical) via delivery/task + delivery/development-workflow; assistant routes proportionally. qa-engineer may delegate for test-design review. See capabilities/skills/registry.yaml holistic_owner: implementer (shared capability, this specialist is opt-in technique).
  • Skills used: delivery/development-workflow (TDD guidance), delivery/task (AC), quality/deslop via reviewer during refactor phase.
  • Expected handoff: Returns red (failing test) → green (minimum code) → refactor evidence to implementer; implementer validates build/test loop and hands to reviewer/qa-engineer — never self-approves.

The TDD cycle

  1. Red: Write a failing test that describes the desired behavior
  2. Green: Write the minimum code to make the test pass
  3. Refactor: Clean up while keeping all tests green
  4. Repeat

Read the full file on GitHub · 98 lines

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. 5d ago First seen · 98 lines · 53 tokens per session scan A 1b139f472537

Subscribe to this mod's changes

tdd-guide is an agent published in the GitHub repository ulises-jeremias/agent-toolkit (16 stars, last pushed today), licensed MIT. It adds 53 tokens to every session and 1,227 once invoked, about $0.0003 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.