carbon-badge

carbon-badge is a skill for Claude Code from gwittebolle/claude-carbon. It costs 20 tokens per session (796 once invoked), scanned A, original, MIT.

A generator for a shields.io badge showing your Claude Code carbon footprint. Shields.io is a service that creates small status images commonly placed in project README files.

In plain words
What is it for?
Use it to create a badge URL or image for a README, based on the carbon-footprint data from your Claude Code setup.
Why use it?
It provides a reusable project badge instead of requiring you to format and maintain the footprint display yourself.

Skill for Claude Code

Written for Claude Code: ${CLAUDE_PLUGIN_ROOT variable. Also seen: positional $N argument; mentions Claude Code.

Runs only inside its plugin — its command needs a path that Claude Code sets for a plugin’s own hooks and for nothing else. Install the plugin, not this.

Part of the claude-carbon plugin — 5 skills, 3 hooks shipped together

Good fit Use it to create a badge URL or image for a README, based on the carbon-footprint data from your Claude Code setup.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.

Claude Code
/plugin marketplace add gwittebolle/claude-carbon
Claude Code
/plugin install claude-carbon

Made for: Claude Code.

Or install claude-carbon, the plugin that ships this one along with the rest of its 5 skills, 3 hooks.

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 carbon-badge

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/gwittebolle/claude-carbon/carbon-badge"><img src="https://agentmods.dev/badge/skills/gwittebolle/claude-carbon/carbon-badge.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 796 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 $0.00020 $0.00796
Opus 5 $0.00010 $0.00398
Sonnet 5 $0.00004 $0.00159
Haiku 4.5 $0.00002 $0.00080

Measured 8d ago against content hash 94ddfcba01b0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

carbon-badge 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 8d 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/carbon-badge/SKILL.md · 53 lines

What it actually says

Run the following bash script and present the output to the user.

#!/usr/bin/env bash
# Locate the install wired into the status line (honours CLAUDE_CONFIG_DIR),
# then fall back to CLAUDE_PLUGIN_ROOT / CLAUDE_CARBON_DIR / the default path.
# Windows (Git Bash): CLAUDE_* variables and the paths stored in settings.json can
# arrive in the native "C:\Users\..." spelling, which bash cannot open. cygpath
# ships with Git for Windows; everywhere else this is the identity function.
ccp() {
  case "${OSTYPE:-}" in msys*|cygwin*) ;; *) printf '%s' "$1"; return 0 ;; esac
  case "$1" in
    [A-Za-z]:[\\/]*|*\\*) cygpath -u "$1" 2>/dev/null || printf '%s' "$1" ;;
    *) printf '%s' "$1" ;;
  esac
}
CFG="$(ccp "${CLAUDE_CONFIG_DIR:-$HOME/.claude}")"
REPO_DIR=""
if command -v jq >/dev/null 2>&1 && [ -f "$CFG/settings.json" ]; then
  SL_CMD="$(jq -r '.statusLine.command // empty' "$CFG/settings.json" 2>/dev/null)"
  # statusLine.command stores a shell-escaped path: expand ~ and unescape spaces
  SL_CMD="${SL_CMD//\\ / }"; SL_CMD="${SL_CMD/#\~/$HOME}"; SL_CMD="$(ccp "$SL_CMD")"
  [ -n "$SL_CMD" ] && [ -f "$SL_CMD" ] && REPO_DIR="$(cd "$(dirname "$SL_CMD")/.." 2>/dev/null && pwd)"
fi
[ -z "$REPO_DIR" ] && [ -n "${CLAUDE_PLUGIN_ROOT:-}" ] && REPO_DIR="$(ccp "$CLAUDE_PLUGIN_ROOT")"
[ -z "$REPO_DIR" ] && [ -n "${CLAUDE_CARBON_DIR:-}" ] && REPO_DIR="$(ccp "$CLAUDE_CARBON_DIR")"
if [ -z "$REPO_DIR" ]; then
  # Pure marketplace installs reach here: no statusLine.command in settings.json and
  # no CLAUDE_PLUGIN_ROOT in a skill's bash env. Pick the newest cached plugin copy,
  # keeping only candidates that ship the badge script.
  CACHE_LATEST=""
  for D in "$CFG/plugins/cache"/*/claude-carbon/*/; do
    [ -f "${D}scripts/generate-badge.sh" ] || continue
    if [ -z "$CACHE_LATEST" ] || [ "$(printf '%s\n%s\n' "$CACHE_LATEST" "$D" | sort -V | tail -1)" = "$D" ]; then
      CACHE_LATEST="$D"
    fi
  done
  [ -n "$CACHE_LATEST" ] && REPO_DIR="${CACHE_LATEST%/}"
fi
[ -z "$REPO_DIR" ] && REPO_DIR="$HOME/code/claude-carbon"

bash "$REPO_DIR/scripts/generate-badge.sh"

The script prints a ready-to-paste markdown snippet and the raw badge URL. Show both exactly as printed — never recompute, reformat or re-escape the number or the URL. Tell the user to paste the markdown line into any README of theirs; the badge is a static image, so re-running /carbon-badge is how they refresh the figure.

If the script is missing (an install that predates the badge), suggest /carbon-update.

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. 8d ago Changed · +10 lines 94ddfcba01b0
  2. 12d ago First seen · 43 lines · 20 tokens per session scan A df0c49c568cf

Subscribe to this mod's changes

carbon-badge is a skill published in the GitHub repository gwittebolle/claude-carbon (193 stars, last pushed yesterday), licensed MIT. It adds 20 tokens to every session and 796 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 2026-08-30.