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/dr-code/tessera/writing-skillsnpx skills add dr-code/tessera --skill writing-skillsgit clone --depth 1 https://github.com/dr-code/tesseraWrote 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/dr-code/tessera/writing-skills)<a href="https://agentmods.dev/skills/dr-code/tessera/writing-skills"><img src="https://agentmods.dev/badge/skills/dr-code/tessera/writing-skills.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 | $0.00020 | $0.00738 |
| Opus 5 | $0.00010 | $0.00369 |
| Sonnet 5 | $0.00004 | $0.00148 |
| Haiku 4.5 | $0.00002 | $0.00074 |
Grade A, and why
writing-skills 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 4d 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 — 118 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Writing Skills
Overview
Writing skills IS Test-Driven Development applied to process documentation.
Write test cases (pressure scenarios), watch them fail (baseline behavior), write the skill, watch tests pass, refactor (close loopholes).
Core principle: If you didn't watch an agent fail without the skill, you don't know if the skill teaches the right thing.
REQUIRED BACKGROUND: Understand test-driven-development before using this skill.
What is a Skill?
A skill is a reference guide for proven techniques, patterns, or tools.
Skills are: Reusable techniques, patterns, tools, reference guides
Skills are NOT: Narratives about how you solved a problem once
SKILL.md Structure
Frontmatter (YAML):
- Two required fields only:
nameanddescription name: letters, numbers, hyphens onlydescription: starts with "Use when...", describes triggering conditions, NOT the skill's workflow
---
name: skill-name
description: Use when [specific triggering conditions]
---
# Skill Name
## Overview
Core principle in 1-2 sentences.
## When to Use
Bullet list with symptoms and use cases
## Core Pattern
Before/after comparison or process steps
## Common Mistakes
What goes wrong + fixes
Claude Search Optimization
Description = When to Use, NOT What the Skill Does
The description answers: "Should I read this skill right now?" It must NOT summarize the workflow.
# BAD: Summarizes workflow — Claude follows this instead of reading the skill
description: Use when executing plans - dispatches subagent per task with review between tasks
# GOOD: Triggering conditions only
description: Use when executing implementation plans with independent tasks in the current session
TDD Mapping for Skills
| TDD Concept | Skill Creation |
|---|---|
| Test case | Pressure scenario with subagent |
| Production code | Skill document (SKILL.md) |
| RED | Agent violates rule without skill (baseline) |
| GREEN | Agent complies with skill present |
| REFACTOR | Close loopholes while maintaining compliance |
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.
- 4d ago First seen · 118 lines · 20 tokens per session scan A 532fd5367076
writing-skills is a skill published in the GitHub repository dr-code/tessera (1 stars, last pushed 24d ago), licensed MIT. It adds 20 tokens to every session and 738 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 2026-08-31.
Other skills, from other repositories
engram-testing-coverage
TDD and coverage standards for Engram. Trigger: When implementing behavior changes in any package.
tdd
Test-driven development. Use when the user wants to build features or fix bugs test-first, mentions "red-green-refactor", or wants integration tests.
strict-tdd
Strict RED->GREEN->REFACTOR test-driven development with enforcement. Never write production code before a failing test. Atomic commits per TDD cycle.
tdd
This skill should be used when the user wants to implement features or fix bugs using test-driven development. Enforces the RED-GREEN-REFACTOR cycle with vertical slicing, context isolation between test writing and implementation, human checkpoints, and auto-test feedback loops. Uses multi-agent orchestration with the…
conductor-implement
Execute tasks from a track's implementation plan following TDD workflow.
mobiai-mobile-tdd
You MUST use this before writing any implementation code for a mobile feature, bug fix, refactor, or behavior change. Tests come before implementation — no exceptions.