Effect vs pencil-dev-skill
Effect is an MCP server published by tim-smart. Marketplaces we read that list it: 1 (Docker MCP Catalog). pencil-dev-skill is a plugin bundle for AI coding tools published by Nisus74. Marketplaces we read that list it: 1 (Claude Code: claude-plugins-community). As of our marketplace pass on 2026-10-13. 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 |   Effect | |
|---|---|---|
| Docker MCP Catalog | Listed Version: sha256:a0e077abc890 Forks (GitHub): 13 Pulls (Docker Hub): 12 862 Stars (Docker Hub): 0 Stars (GitHub): 239 Not marked · First seen |
Not listed |
| Claude Code: claude-plugins-community | Not listed | Listed Version: 0.8.0 Forks (GitHub): 2 Stars (GitHub): 25 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 | Effect | pencil-dev-skill |
|---|---|---|
| Marketplaces that list it | 1 | 1 |
| Stars (GitHub) (differs) | 239 (better) | 25 (worse) |
| Pulls (Docker Hub) (differs) | 12 862 | No figure on Docker Hub |
| Forks (GitHub) (differs) | 13 (better) | 2 (worse) |
| Last release | Not published | Not published |
| Where it runs (differs) | On your machine (mcp/effect-mcp) | Installs as a plugin bundle |
| Transport (differs) | stdio | Not stated |
| Tools it declares (differs) | 2 | Not published |
| Environment variables it asks for | Not published | Not published |
| Parts of the bundle (differs) | Not a bundle | 1 |
| Licence | MIT | MIT |
| Repository (differs) | github.com/tim-smart/effect-mcp | github.com/nisus74/pencil-skill |
| 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
Effect
Tools and resources for writing Effect code in Typescript.
pencil-dev-skill
Teaches AI coding tools to design and edit pencil.dev UI files (.pen format) through the Pencil MCP server. Every read and write goes through the MCP for schema validation. Live screenshots show the design as it looks, and the MCP keeps your changes and the editor in sync while the canvas is open. Recognises pencil.dev signals automatically: mentions of .pen, .lib.pen, the Pencil canvas, or a design-system folder all activate the skill. Works with Claude Code, Codex, Gemini CLI, Copilot CLI, and Cursor. Supports designing screens from scratch, editing existing canvases, instantiating components from .lib.pen libraries, customising design tokens, and bulk-replacing properties across a project.
How to run each
Effect As a local MCP server: Docker image
claude mcp add --transport stdio effect-mcp -- docker run -i --rm mcp/effect-mcppencil-dev-skill
No data for an automatic command: what its marketplaces declare does not say unambiguously how to connect it.
Commands built only from what the marketplaces declare; the full set for every client is on each card.
Tools each declares
The marketplaces of pencil-dev-skill publish no list of tools, so we do not compare tools.
Settings each asks for
Neither one's marketplaces publish the settings it asks for.
What it can do: Effect · What it can do: pencil-dev-skill · Compare two other plugins
Data comes from the Docker MCP Catalog (desktop.docker.com/mcp/catalog) and Docker Hub. Data comes from the public marketplace file https://github.com/anthropics/claude-plugins-community/blob/HEAD/.claude-plugin/marketplace.json. Figures come from our own regular passes over the marketplaces, last read on . We publish no contact details for plugin publishers.