baseline-ui

baseline-ui is a skill for Claude Code, Codex from vercel-labs/open-agents. It costs 48 tokens per session (777 once invoked), scanned A, a copy of baseline-ui, MIT.

A set of checks for React and Tailwind CSS interfaces, covering animation timing, text sizing, accessibility, and reusable component patterns.

In plain words
What is it for?
Use it when building or reviewing UI components, styling React views, checking icon buttons and focus behavior, or enforcing design rules.
Why use it?
It catches common interface problems that can make a page inconsistent, difficult to use, or hard to navigate with a keyboard.

Skill for Claude CodeCodex ✓ vendor

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

Good fit Use it when building or reviewing UI components, styling React views, checking icon buttons and focus behavior, or enforcing design rules.

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Install with agentmods
npx agentmods add skills/vercel-labs/open-agents/baseline-ui
About the project

Open Agents is an open-source reference application for running background coding agents through a web interface, durable workflows, isolated Vercel sandboxes, and GitHub integration. Developers fork and adapt it to let agents make code changes without keeping a local computer running. The catalogue entries provide skills, agents, and instructions for its workflow.

vercel-labs/open-agents · 5,805 stars · on GitHub · open-agents.dev

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add vercel-labs/open-agents --skill baseline-ui
Clone the repo
git clone --depth 1 https://github.com/vercel-labs/open-agents

Made for: Claude Code, Codex.

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 baseline-ui

README.md
[![agentmods](https://agentmods.dev/badge/skills/vercel-labs/open-agents/baseline-ui.svg)](https://agentmods.dev/skills/vercel-labs/open-agents/baseline-ui)
Your own site
<a href="https://agentmods.dev/skills/vercel-labs/open-agents/baseline-ui"><img src="https://agentmods.dev/badge/skills/vercel-labs/open-agents/baseline-ui.svg" alt="Measured on agentmods" height="20"></a>
Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 777 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 86% copy Near-identical to another mod 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 $0.00048 $0.00777
Opus 5 $0.00024 $0.00388
Sonnet 5 $0.00010 $0.00155
Haiku 4.5 $0.00005 $0.00078

Measured 6d ago against content hash 9bb2f868098a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

baseline-ui 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 6d 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.

Origin

This is a copy

86% identical to baseline-ui — 2 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/baseline-ui/SKILL.md · 86 lines

How it starts

The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Baseline UI

Enforces an opinionated UI baseline to prevent AI-generated interface slop.

How to use

  • /baseline-ui Apply these constraints to any UI work in this conversation.

  • /baseline-ui <file> Review the file against all constraints below and output:

    • violations (quote the exact line/snippet)
    • why it matters (1 short sentence)
    • a concrete fix (code-level suggestion)

Stack

  • MUST use Tailwind CSS defaults unless custom values already exist or are explicitly requested
  • MUST use motion/react (formerly framer-motion) when JavaScript animation is required
  • SHOULD use tw-animate-css for entrance and micro-animations in Tailwind CSS
  • MUST use cn utility (clsx + tailwind-merge) for class logic

Components

  • MUST use accessible component primitives for anything with keyboard or focus behavior (Base UI, React Aria, Radix)
  • MUST use the project’s existing component primitives first
  • NEVER mix primitive systems within the same interaction surface
  • SHOULD prefer Base UI for new primitives if compatible with the stack
  • MUST add an aria-label to icon-only buttons
  • NEVER rebuild keyboard or focus behavior by hand unless explicitly requested

Interaction

  • MUST use an AlertDialog for destructive or irreversible actions
  • SHOULD use structural skeletons for loading states
  • NEVER use h-screen, use h-dvh
  • MUST respect safe-area-inset for fixed elements
  • MUST show errors next to where the action happens
  • NEVER block paste in input or textarea elements

Animation

  • NEVER add animation unless it is explicitly requested
  • MUST animate only compositor props (transform, opacity)
  • NEVER animate layout properties (width, height, top, left, margin, padding)
  • SHOULD avoid animating paint properties (background, color) except for small, local UI (text, icons)
  • SHOULD use ease-out on entrance
  • NEVER exceed 200ms for interaction feedback
  • MUST pause looping animations when off-screen
  • SHOULD respect prefers-reduced-motion
  • NEVER introduce custom easing curves unless explicitly requested
  • SHOULD avoid animating large images or full-screen surfaces

Read the full file on GitHub · 86 lines

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. 6d ago First seen · 86 lines · 48 tokens per session scan A 9bb2f868098a

Subscribe to this mod's changes

baseline-ui is a skill published in the GitHub repository vercel-labs/open-agents (5,805 stars, last pushed 8d ago), licensed MIT. It adds 48 tokens to every session and 777 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 86% identical to baseline-ui, differing in 2 lines, and is treated as a copy.