co2-tracker vs ai.circulara/plugin
co2-tracker is a plugin bundle for AI coding tools published by gwittebolle. Marketplaces we read that list it: 1 (Claude Code: claude-plugins-community). ai.circulara/plugin is an MCP server published by circulara.ai. Marketplaces we read that list it: 1 (Official MCP Registry). As of our marketplace pass on 2026-10-18. This pair was picked by a reader, not by our comparison rule, so search engines are asked not to index the page.
Where each is published
| Marketplace |  co2-tracker | |
|---|---|---|
| Claude Code: claude-plugins-community | Listed Version: 1.1.2 Forks (GitHub): 18 Stars (GitHub): 216 Not marked · First seen |
Not listed |
| Official MCP Registry | Not listed | Listed Version: 0.1.2 Downloads/month (npm): 229 Downloads/week (npm): 47 Not marked · First seen |
Each figure is the marketplace's own and is never added up across marketplaces. A marketplace that publishes no figure shows none: no number is not zero.
The facts side by side
| Fact | co2-tracker | ai.circulara/plugin |
|---|---|---|
| Marketplaces that list it | 1 | 1 |
| Stars (GitHub) (differs) | 216 | No figure on GitHub |
| Forks (GitHub) (differs) | 18 | No figure on GitHub |
| Last release | Not published | Not published |
| Where it runs (differs) | Installs as a plugin bundle | On your machine (@circulara/plugin) |
| Transport (differs) | Not stated | stdio |
| Tools it declares | Not published | Not published |
| Environment variables it asks for (differs) | Not published | 5, secrets among them: 1 |
| Hooks it runs (differs) | 2 | Not published |
| Parts of the bundle (differs) | 5 | Not a bundle |
| Licence (differs) | MIT | Not stated |
| Repository (differs) | github.com/gwittebolle/claude-carbon | github.com/circularroute/circulara-core |
| Changes in the last 7 days | 0 | 0 |
| First seen | 2026-10-11 | 2026-10-11 |
Lines where the two differ have a tinted background and bold values. Where the data itself says which value is better (more marketplaces, a larger figure of the same marketplace, a fresher release, a verified mark on a marketplace that lists both), the better one is also marked green with ▲ and the worse one red with ▼. Where it runs, the transport, the tools, the settings, hooks, the bundle's parts, the licence and the week's changes are marked only as different: more or fewer is not better in itself.
What each says it does
co2-tracker
Track the carbon footprint of your Claude Code sessions. Adds a live CO2 estimate to the status line, persists sessions to a local SQLite database, and generates shareable PNG report cards. Based on peer-reviewed emission factors from Jegham et al. 2025.
ai.circulara/plugin
Circulara Observe MCP plugin - meters your AI agents' token spend and carbon, free tier.
How to run each
co2-tracker As a Claude Code plugin
/plugin marketplace add anthropics/claude-plugins-community
/plugin install co2-tracker@claude-communityai.circulara/plugin As a local MCP server: npm package
claude mcp add --env "CIRCULARA_BACKEND_URL=<YOUR_CIRCULARA_BACKEND_URL>" --env "CIRCULARA_SEAT_ID=<YOUR_CIRCULARA_SEAT_ID>" --env "CIRCULARA_TENANT_ID=<YOUR_CIRCULARA_TENANT_ID>" --env "CIRCULARA_TOKEN=<YOUR_CIRCULARA_TOKEN>" --env "CIRCULARA_USER_ID=<YOUR_CIRCULARA_USER_ID>" --transport stdio plugin -- npx -y -p @circulara/plugin circulara-mcp @circulara/pluginRequires: CIRCULARA_BACKEND_URL, CIRCULARA_SEAT_ID, CIRCULARA_TENANT_ID, CIRCULARA_TOKEN (secret), CIRCULARA_USER_ID
Commands built only from what the marketplaces declare; the full set for every client is on each card.
Tools each declares
Neither one's marketplaces publish a list of tools, so there is nothing to compare.
Settings each asks for
The marketplaces of co2-tracker publish no settings it asks for, so we do not compare settings.
What it can do: co2-tracker · What it can do: ai.circulara/plugin · Compare two other plugins
Data comes from the public marketplace file https://github.com/anthropics/claude-plugins-community/blob/HEAD/.claude-plugin/marketplace.json. Data comes from the Official MCP Registry (registry.modelcontextprotocol.io), CC0 1.0. Figures come from our own regular passes over the marketplaces, last read on . We publish no contact details for plugin publishers.