Effect Skill (Effect-TS) for Claude Code: What It Does and How to Install It

Sets up a repo to use the Effect TypeScript library: installs it and tells your agent to read the guide that ships in the package.

Installs: 8.4K; on skills.sh
Stars: 114; on GitHub
Updated: Oct 2026; last repo commit

SKILL.md has two steps. First it installs effect with your package manager. Then it makes sure your AGENTS.md or CLAUDE.md contains a block that tells the agent to read node_modules/effect/AGENTS.md completely before writing Effect code.

It loads when you set up a repository that uses the Effect TypeScript library. It bundles no scripts. The main guidance comes from the installed package, so it follows the version you install.

Good for

TypeScript developers starting to use Effect in a repo
Teams that want agents to follow the Effect guide in node_modules

Install effect-ts

Claude Code

Copy this prompt.

Install the effect-ts skill in Claude Code. Run this command:

npx skills add Effect-TS/skills

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

Requires Node.js.

The README command installs both skills in the repo: effect-ts and effect-v3-to-v4. The single-skill route installs effect-ts only. The skill runs your package manager, so there is no Claude app upload route.

From the project README. Source.

What's in the skill

When it loads

Use this skill when setting up a repository that uses the Effect Typescript library.

Key facts

Author: Effect-TS (Effectful Technologies Inc, vendor's own repo)
Repo: effect-ts/skills
License: MIT (LICENSE)
Installs on skills.sh: 8,360 (Nov 2, 2026)
GitHub stars: 114 for the whole Effect-TS/skills repo (Nov 2, 2026)
Last repo commit: Oct 9, 2026
Audits on skills.sh: Gen Agent Trust Hub: pass, Socket: pass, Snyk: pass
What it includes: 1 file: SKILL.md (counted from the repo tree)
Sibling skill: effect-v3-to-v4 in the same repo, for Effect v3 to v4 migration

What it includes

Adds the effect package with your package manager; SKILL.md shows pnpm add effect@latest.
In a monorepo SKILL.md says to install it as a dev dependency at the root, so the source is at node_modules/effect/src.
Try: “Set up this repo to use Effect.”
Runs code · Step 1: Install effect
Adds a "Learning more about Effect" block to your agent instructions.
The block tells the agent to read node_modules/effect/AGENTS.md completely before writing Effect code, and to search node_modules/effect/src for other APIs.
Write · Step 2: Update AGENTS.md / CLAUDE.md

From the official docs

Permissions

Low risk

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

It installs effect@latest
SKILL.md runs the install with your package manager and shows pnpm add effect@latest, which takes the newest release. Pin a version yourself if your project needs one. github.com
It edits your agent instruction files
Step 2 adds a block to AGENTS.md or CLAUDE.md. Check the diff before committing. github.com

Technical details

Turning on read-only	No read-only mode is documented.
Talks to	npm registry (installing effect@latest)
Scopes	Installs the effect package, which changes package.json and your lockfile Edits AGENTS.md or CLAUDE.md in your repo

Questions

What does the effect-ts skill do?

It sets up a repo to use the Effect TypeScript library with an agent. It installs effect, then adds a note to AGENTS.md or CLAUDE.md that sends the agent to the guide shipped inside the package.

How do I install it?

Use the install box at the top of this page. The README gives one skills CLI command that installs both skills in the repo.

Does it need an API key?

No key or sign-in is named in SKILL.md or the README. It uses your package manager to install effect.

Is it safe?

It bundles no scripts. Its steps install a package and edit your agent instruction file. Our advice: run it in a git repo and review the changes.

What is the difference between effect-ts and effect-v3-to-v4?

The README says effect-ts points agents to the guidance in the installed package, and effect-v3-to-v4 is a bounded migration skill for upgrading from Effect v3 to v4. The repo ships both.

Is it official?

Yes, in the sense that it is in the vendor's own repo: the Effect-TS GitHub organization, with a LICENSE naming Effectful Technologies Inc. The README does not use the word official.

Why is SKILL.md so short?

The README says the skill relies on the package's own AGENTS.md so guidance stays in line with the installed Effect version. SKILL.md has 2 steps.

Information

updated Nov 2, 2026

Repository: effect-ts/skills
Folder: skills/effect-ts

effect-ts/skills skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 2

Effect-TS/skills README · github.com
effect-ts SKILL.md · github.com