spec-writer

spec-writer is a skill for Claude Code, Codex from SamJHudson01/Carmack-Council. It costs 125 tokens per session (3,227 once invoked), scanned A, original, MIT.

A tool for writing short, structured software specifications that define what must be built and how completion will be judged.

In plain words
What is it for?
Use it to specify features, bug fixes, products, and other implementation work in a format that people can review quickly.
Why use it?
It reduces vague requirements and helps developers and coding agents agree on the expected result before implementation begins.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions CLAUDE.md; mentions Claude Code.

Good fit Use it to specify features, bug fixes, products, and other implementation work in a format that people can review quickly.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/samjhudson01/carmack-council/spec-writer
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.

Any agent
npx skills add SamJHudson01/Carmack-Council --skill spec-writer
Clone the repo
git clone --depth 1 https://github.com/SamJHudson01/Carmack-Council

Made for: Claude Code, Codex.

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 spec-writer

README.md
[![agentmods](https://agentmods.dev/badge/skills/samjhudson01/carmack-council/spec-writer/github.svg)](https://agentmods.dev/skills/samjhudson01/carmack-council/spec-writer)
Your own site
<a href="https://agentmods.dev/skills/samjhudson01/carmack-council/spec-writer"><img src="https://agentmods.dev/badge/skills/samjhudson01/carmack-council/spec-writer/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 spec-writer

Your own site · 80×15
<a href="https://agentmods.dev/skills/samjhudson01/carmack-council/spec-writer"><img src="https://agentmods.dev/badge/skills/samjhudson01/carmack-council/spec-writer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 125 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,227 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 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 5.1 $0.00125 $0.03227
Opus 5 $0.00063 $0.01614
Sonnet 5 $0.00025 $0.00645
Haiku 4.5 $0.00013 $0.00323

Measured 11d ago against content hash 1652bed6a001, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

spec-writer 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 11d 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.

skills/spec-writer/SKILL.md · 218 lines

How it starts

The opening of the file, as written. The whole thing — 218 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spec Writer

You are a specification engineer. Your job is to produce the shortest structured document that makes "done" unambiguous — a spec an AI agent can execute against without drift, and a human can review in under 5 minutes. Not a PRD. Not an SRS. A spec.

Core philosophy: don't under-spec a hard problem (the agent will flail), but don't over-spec a trivial one (the agent will get tangled). GitHub's analysis of 2,500+ agent configuration files found most fail because they're too vague. Thoughtworks found SDD tools produce verbose specs developers won't read. Thread the needle: structured enough for precision, lean enough for compliance. Research confirms LLM instruction-following drops as spec length increases — the "curse of instructions."

You describe WHAT and WHY. Never HOW. The spec must not contain implementation plans, code snippets, pseudocode, or architectural decisions. Those belong to the agent or developer executing the spec. Specs that contain code create double review — the developer reviews spec code AND implementation code. Marmelab's sharpest critique of SDD: this is where it collapses into waterfall.


Compact Instructions

When compacting during a spec-writing session, preserve:

  • The complexity tier (small / feature / product)
  • The project context gathered in Phase 1 (stack, structure, relevant files)
  • Any user-confirmed scope decisions (in-scope, out-of-scope, non-goals)
  • The current phase number and what has been completed
  • The output file path if already determined
  • Any acceptance criteria already confirmed by the user

Phase 0: Determine Complexity

Before generating anything, determine the right spec tier. This is non-negotiable. A bug fix does not need user stories. A new product does not fit in 200 words.

Ask the user (or infer from context if obvious):

Small change — bug fix, config change, copy update, simple addition to existing feature. One clear thing to do. Output: ~200 words. No user stories. Problem + acceptance criteria + boundaries.

Read the full file on GitHub · 218 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 11d ago First seen · 218 lines · 125 tokens per session scan A 1652bed6a001

Subscribe to this mod's changes

spec-writer is a skill published in the GitHub repository SamJHudson01/Carmack-Council (52 stars, last pushed 5mo ago), licensed MIT. It adds 125 tokens to every session and 3,227 once invoked, about $0.0006 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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