openui

openui is a skill for Claude Code, Codex from TommyBez/evex. It costs 31 tokens per session (411 once invoked), scanned A, original, MIT.

Instructions for OpenUI Lang, a format in which an assistant reply describes a user interface that a chat application can render.

In plain words
What is it for?
Building chat cards, tables, lists, and follow-up controls, and troubleshooting invalid or incomplete generated interfaces.
Why use it?
It helps prevent replies that the interface cannot parse or display, such as missing definitions or unsupported layout elements.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/tommybez/evex/openui
Any agent
npx skills add TommyBez/evex --skill openui
Clone the repo
git clone --depth 1 https://github.com/TommyBez/evex

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 openui

README.md
[![agentmods](https://agentmods.dev/badge/skills/tommybez/evex/openui.svg)](https://agentmods.dev/skills/tommybez/evex/openui)
Your own site
<a href="https://agentmods.dev/skills/tommybez/evex/openui"><img src="https://agentmods.dev/badge/skills/tommybez/evex/openui.svg" alt="Measured on agentmods" height="20"></a>
Per session 31 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 411 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found 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 $0.00031 $0.00411
Opus 5 $0.00015 $0.00205
Sonnet 5 $0.00006 $0.00082
Haiku 4.5 $0.00003 $0.00041

Measured 5d ago against content hash c5e789e5878b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

openui 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 5d 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.

registry/openui-assistant/agent/skills/openui/SKILL.md · 44 lines

What it actually says

OpenUI Lang

Every assistant reply is an OpenUI Lang program whose first statement assigns root. This agent uses openuiChatLibrary from @openuidev/react-ui/genui-lib (the same library as the official openui-chat example). The build-time system prompt comes from openuiChatLibrary.prompt(openuiChatPromptOptions).

Chat library constraints

openuiChatLibrary centers on chat primitives: Card, CardHeader, TextContent, Table, lists, and follow-ups. Do not use Stack; it belongs to the broader OpenUI library, not this agent's chat library.

For a layout example, see syntax-examples.

Debugging checklist

  1. Confirm the reply starts with root = ...
  2. Confirm every referenced identifier is defined
  3. Confirm tool-backed values match the latest tool JSON
  4. Remove markdown fences or prose around the program
  5. Re-run with a smaller layout if the stream was truncated

Done when each item is confirmed or ruled out and the reply is a valid OpenUI Lang program starting with root =.

Frontend integration

For Next.js + Eve wiring (dependencies, withEve(), OpenUIEveChat, accessibility, smoke tests), see frontend-wiring.

External references

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 5d ago First seen · 44 lines · 31 tokens per session scan A c5e789e5878b

Subscribe to this mod's changes

openui is a skill published in the GitHub repository TommyBez/evex (24 stars, last pushed today), licensed MIT. It adds 31 tokens to every session and 411 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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