carbon: Skill for Claude Code

.claude/skills/spec-writing/SKILL.md

spec-writing is a skill for Claude Code from crbnos/carbon. It costs 119 tokens per session (2,359 once invoked), scanned A, original, no licence file.

A feature-design process that produces a written specification in the repository. It includes competitor research, design decisions, and a discussion with the user to settle open questions before writing the document.

In plain words
What is it for?
Use it when planning a new feature or module, or when brainstorming one. It writes the result to a dated Markdown file under .ai/specs/.
Why use it?
It prevents important product and technical decisions from being left unclear while implementation begins. The resulting spec gives the team a shared description of what should be built.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is crbnos/carbon's own configuration. It tells Claude Code how to work on carbon itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything carbon configures →

Reuse

Borrowing it

Nothing to install: this file belongs to crbnos/carbon. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/crbnos/carbon/main/.claude/skills/spec-writing/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/crbnos/carbon

Made for: Claude Code.

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-writing

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/crbnos/carbon/spec-writing"><img src="https://agentmods.dev/badge/skills/crbnos/carbon/spec-writing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 119 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,359 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 2 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Agent Snooping · line 98
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
  • medium Excessive Agency · line 184
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
How audits are shown
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 $0.00119 $0.02359
Opus 5 $0.00060 $0.01179
Sonnet 5 $0.00024 $0.00472
Haiku 4.5 $0.00012 $0.00236

Measured 9d ago against content hash d15d0e2d73f9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

spec-writing 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 9d 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.

.claude/skills/spec-writing/SKILL.md · 197 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

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. 9d ago First seen · 197 lines · 119 tokens per session scan A d15d0e2d73f9

Subscribe to this mod's changes

spec-writing is a skill published in the GitHub repository crbnos/carbon (2,397 stars, last pushed today), with no licence file. It adds 119 tokens to every session and 2,359 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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