Web Artifacts Builder
anthropics/skills
Builds multi-component claude.ai HTML artifacts as a small React, TypeScript and Tailwind project, then bundles it into one shareable HTML file.
Enforces Effect-TS patterns for services, errors, layers, and atoms.
Install Effect Best Practices
$ npx skills add millionco/expect --skill effect-best-practices -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install millionco/expect effect-best-practices --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/millionco/expect.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/effect-best-practices .claude/skills/effect-best-practices && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "effect-best-practices" agent skill from https://github.com/millionco/expect/tree/main/.agents/skills/effect-best-practices into .claude/skills/effect-best-practices/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "effect-best-practices", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/millionco/expect/tree/main/.agents/skills/effect-best-practicesType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add millionco/expect --skill effect-best-practices -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install millionco/expect effect-best-practices --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/millionco/expect.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.agents/skills/effect-best-practices .agents/skills/effect-best-practices && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "effect-best-practices" agent skill from https://github.com/millionco/expect/tree/main/.agents/skills/effect-best-practices into .agents/skills/effect-best-practices/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "effect-best-practices", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add millionco/expect --skill effect-best-practices -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install millionco/expect effect-best-practices --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/millionco/expect.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.agents/skills/effect-best-practices .cursor/skills/effect-best-practices && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "effect-best-practices" agent skill from https://github.com/millionco/expect/tree/main/.agents/skills/effect-best-practices into .cursor/skills/effect-best-practices/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "effect-best-practices", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/millionco/expect.git --path .agents/skills/effect-best-practices--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add millionco/expect --skill effect-best-practices -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install millionco/expect effect-best-practices --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/millionco/expect.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.agents/skills/effect-best-practices .gemini/skills/effect-best-practices && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "effect-best-practices" agent skill from https://github.com/millionco/expect/tree/main/.agents/skills/effect-best-practices into .gemini/skills/effect-best-practices/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "effect-best-practices", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install millionco/expect effect-best-practicesInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add millionco/expect --skill effect-best-practices -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/millionco/expect.git skills-src && mkdir -p .github/skills && cp -r skills-src/.agents/skills/effect-best-practices .github/skills/effect-best-practices && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "effect-best-practices" agent skill from https://github.com/millionco/expect/tree/main/.agents/skills/effect-best-practices into .github/skills/effect-best-practices/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "effect-best-practices", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add millionco/expect --skill effect-best-practices -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install millionco/expect effect-best-practices --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/millionco/expect.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.agents/skills/effect-best-practices .opencode/skills/effect-best-practices && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "effect-best-practices" agent skill from https://github.com/millionco/expect/tree/main/.agents/skills/effect-best-practices into .opencode/skills/effect-best-practices/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "effect-best-practices", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
effect-best-practices- GitHub stars
- 3.6k
- Token cost
- ~3.8k tokens
- SKILL.md length
- 485 words
- Files
- 9 (incl. references)
- Skills in repo
- 5
- Repo updated
- First seen
- Licence
- Custom licence
At a glance
Enforces Effect-TS patterns for services, errors, layers, and atoms.
- Writing code with Effect.Service
- SKILL.md covers Quick Reference: Critical Rules, Service Definition Pattern, Error Definition Pattern and Schema & Branded Types Pattern, plus 8 more sections
- Needs API_KEY
- Schema.TaggedError
What it does
Effect Best Practices is an agent skill from millionco/expect. Enforces Effect-TS patterns for services, errors, layers, and atoms. Use when writing code with Effect.Service, Schema.TaggedError, Layer composition, or effect-atom React components.
Its SKILL.md is about 3.8k tokens, which your agent loads only when the skill is triggered. The skill folder holds 9 other files, including reference files (for example `references/anti-patterns.md`, `references/effect-atom-patterns.md` and `references/error-patterns.md`).
It sits in Frontend & Design, covering React components. The repository describes itself as: Expect tests your agent's code in a real browser.
When your agent uses it
- Writing code with Effect.Service
- Schema.TaggedError
- Layer composition
- Effect-atom React components
Example prompts
- “Use the effect-best-practices skill to enforce Effect-TS patterns for services, errors, layers, and atoms”
- “/effect-best-practices”
What it can do on your machine
Read from SKILL.md and the folder at commit 39e9750. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are typescript).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names these keys or tokens, usually read from environment variables:
API_KEY
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Effect Best Practices loads about 3.8k tokens when it runs, and up to ~24k if it reads all its reference files. Until then it costs about 51 tokens; SKILL.md has 485 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 485 words (~3,811 tokens).
“This skill enforces opinionated, consistent patterns for Effect-TS codebases. These patterns optimize for type safety, testability, observability, and maintainability.”
- name
- effect-best-practices
- version
- 1.0.0
Files
SKILL.md and 8 other files (references) in .agents/skills/effect-best-practices of millionco/expect.
- SKILL.md
- references/anti-patterns.md
- references/effect-atom-patterns.md
- references/error-patterns.md
- references/layer-patterns.md
- references/observability-patterns.md
- references/rpc-cluster-patterns.md
- references/schema-patterns.md
- references/service-patterns.md
Open the folder on GitHubat commit 39e9750
Compare with similar skills
Effect Best Practices next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Effect Best Practices this skillmillionco/expect | 3.6k | — | ~3.8k | Automated safety check: Pass | Custom licence | |
| Web Artifacts Builderanthropics/skills | 180k | 41 repos | ~769 | Automated safety check: Pass | Apache-2.0 | |
| Tailwindcss Developmentanonaddy/anonaddy | 4.9k | 10 repos | ~865 | Automated safety check: Pass | MIT | |
| Core Component Library PatternsChrisWiles/claude-code-showcase | 6.1k | 8 repos | ~1.2k | Automated safety check: Pass | None | |
| React Router Developmentremix-run/react-router | 57k | 1 repos | ~1.5k | Automated safety check: Pass | MIT | |
| React UI State PatternsChrisWiles/claude-code-showcase | 6.1k | 8 repos | ~1.6k | Automated safety check: Pass | None |
Similar skills
- Official
Tailwindcss Development
anonaddy/anonaddy
Always invoke when the user's message includes 'tailwind' in any form.
Core Component Library Patterns
ChrisWiles/claude-code-showcase
Reference for building UI with a token-based core component library: spacing, color and typography tokens, Box, stacks, Text, Button, Input and Card, plus layout patterns.
React Router Development
remix-run/react-router
Guides work on React Router apps by first identifying whether the app uses Framework, Data or Declarative mode, then loading the matching reference and the installed package docs.
React UI State Patterns
ChrisWiles/claude-code-showcase
Sets patterns for React interfaces: when to show loading spinners or skeletons, how to surface errors, how to disable buttons during async work and how to handle empty lists.
Chakra UI v3 Builder
chakra-ui/chakra-ui
Builds responsive, accessible Chakra UI v3 components and layouts, sets up Chakra in new or existing projects, and designs themes with tokens, semantic tokens and recipes.
More from millionco/expect
Debug Agent
millionco/expect
Systematic evidence-based debugging using runtime logs. An agent skill from millionco/expect.
Effect Portable Patterns
millionco/expect
Portable Effect patterns for robust promise execution. An agent skill from millionco/expect.
Expect
millionco/expect
A skill your agent uses when editing .tsx/.jsx/.css/.html, React components, pages, routes, forms, styles, or layouts.
Skill Writing
millionco/expect
Write and improve agent skills (SKILL.md files). An agent skill from millionco/expect.
Related
Categories
Questions about Effect Best Practices
What does Effect Best Practices do?
Enforces Effect-TS patterns for services, errors, layers, and atoms. Effect Best Practices is an agent skill from millionco/expect. Enforces Effect-TS patterns for services, errors, layers, and atoms.
When should I use Effect Best Practices?
Effect Best Practices fits situations like: writing code with Effect.Service; schema.TaggedError; layer composition; effect-atom React components.
How do I install Effect Best Practices in Claude Code?
Run `npx skills add millionco/expect --skill effect-best-practices -a claude-code`. Or copy the skill folder (.agents/skills/effect-best-practices in millionco/expect) into .claude/skills/effect-best-practices in your project. Claude Code loads it when a task matches its description.
How do I install Effect Best Practices in Codex?
Run `npx skills add millionco/expect --skill effect-best-practices -a codex`. Or copy the skill folder (.agents/skills/effect-best-practices in millionco/expect) into .agents/skills/effect-best-practices in your project. Codex loads it when a task matches its description.
Can I use Effect Best Practices in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add millionco/expect --skill effect-best-practices -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/effect-best-practices, .gemini/skills/effect-best-practices, .github/skills/effect-best-practices and .opencode/skills/effect-best-practices in your project.
What does Effect Best Practices need to run?
Going by SKILL.md and its folder, Effect Best Practices needs credentials named API_KEY.
Does Effect Best Practices access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Effect Best Practices safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Effect Best Practices use?
Effect Best Practices has a licence file (the repository's licence) that doesn't match a standard licence. Read it on GitHub before reusing the skill.
How many tokens does Effect Best Practices use?
About 3.8k tokens (SKILL.md is roughly 15k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 21k tokens, read only when the agent opens those files.
What are the alternatives to Effect Best Practices?
Skills that share tags, products or a category with Effect Best Practices: Web Artifacts Builder (anthropics/skills, 180k stars), Tailwindcss Development (anonaddy/anonaddy, 4.9k stars), Core Component Library Patterns (ChrisWiles/claude-code-showcase, 6.1k stars) and React Router Development (remix-run/react-router, 57k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Effect Best Practices?
millionco (a GitHub organization) maintains it in millionco/expect, which has 3,558 GitHub stars. The repository holds 5 skills in this directory. The repository was last updated on May 6, 2026.
Source: millionco/expect on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.