gsd-ui-checker

gsd-ui-checker is an agent for Claude Code from open-gsd/gsd-core. It costs 42 tokens per session (3,048 once invoked), scanned A, original, MIT.

A read-only checker for a UI-SPEC.md file, which is a written contract describing how a user interface should look and behave. It reviews the contract across seven quality areas and returns block, flag, or pass findings.

In plain words
What is it for?
It is for checking UI design contracts, including labels, empty and error states, colors, typography, spacing, and component rules.
Why use it?
A detailed design specification can still contain vague controls, missing error states, inconsistent spacing, or other design problems before implementation starts.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: reads .claude/ paths; mentions CLAUDE.md; mentions AGENTS.md.

Part of the gsd-core plugin — 72 skills, 64 agents, 7 hooks shipped together

Good fit It is for checking UI design contracts, including labels, empty and error states, colors, typography, spacing, and component rules.

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Install with agentmods
npx agentmods add agents/open-gsd/gsd-core/gsd-ui-checker.compact
About the project

GSD Core is a framework that guides AI coding agents through a repeatable cycle of discussing decisions, planning, executing, verifying, and shipping software work. It is used with coding-agent runtimes to organize research and implementation in fresh-context subagents and reduce context degradation. The catalogue entries are its skills, agents, hooks, plugin, and instructions for those workflows.

open-gsd/gsd-core · 9,368 stars · on GitHub · opengsd.net

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.

Clone the repo
git clone --depth 1 https://github.com/open-gsd/gsd-core

Made for: Claude Code.

Or install gsd-core, the plugin that ships this one along with the rest of its 72 skills, 64 agents, 7 hooks.

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 gsd-ui-checker

README.md
[![agentmods](https://agentmods.dev/badge/agents/open-gsd/gsd-core/gsd-ui-checker.compact/github.svg)](https://agentmods.dev/agents/open-gsd/gsd-core/gsd-ui-checker.compact)
Your own site
<a href="https://agentmods.dev/agents/open-gsd/gsd-core/gsd-ui-checker.compact"><img src="https://agentmods.dev/badge/agents/open-gsd/gsd-core/gsd-ui-checker.compact/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for gsd-ui-checker

Your own site · 80×15
<a href="https://agentmods.dev/agents/open-gsd/gsd-core/gsd-ui-checker.compact"><img src="https://agentmods.dev/badge/agents/open-gsd/gsd-core/gsd-ui-checker.compact.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 42 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,048 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 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 5.1 $0.00042 $0.03048
Opus 5 $0.00021 $0.01524
Sonnet 5 $0.00008 $0.00610
Haiku 4.5 $0.00004 $0.00305

Measured 2d ago against content hash 7cf61862ac88, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

gsd-ui-checker 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 2d 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.

agents/gsd-ui-checker.compact.md · 278 lines

How it starts

The opening of the file, as written. The whole thing — 278 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spawned by /gsd:ui-phase orchestrator (after gsd-ui-researcher creates UI-SPEC.md) or re-verification (after researcher revises).

CRITICAL: Mandatory Initial Read. If the prompt contains a <required_reading> block, use the Read tool to load every file listed there before performing any other actions. Primary context.

Critical mindset: a UI-SPEC can have every section filled in and still produce design debt — generic CTA labels ("Submit", "OK", "Cancel"); missing empty/error states or placeholder copy; accent color reserved for "all interactive elements" (defeats the purpose); more than 4 font sizes (visual chaos); spacing values not multiples of 4 (breaks grid alignment); third-party registry blocks without a safety gate; a component inventory recalled rather than enumerated (reads as authoritative, binds as a closed allowlist, caps the whole phase).

You are read-only — never modify UI-SPEC.md. Report findings, let the researcher fix.

<adversarial_stance> FORCE stance: assume every UI-SPEC.md contains design debt until the contract proves otherwise — generic CTAs, missing states, grid-breaking values are present; find them.

How UI checkers go soft (avoid these): passing a spec because all sections are filled in without checking content quality; treating "accent color defined" as sufficient without checking it's reserved; accepting >4 font sizes or non-4-multiple spacing as "close enough"; letting a polished-looking spec bias toward PASS before each dimension is checked; softening a BLOCK to FLAG to avoid sending the researcher back.

Verdict classification — every dimension resolves to: BLOCK (contract incomplete/inconsistent/unimplementable; planning must not begin), FLAG (works but degrades design quality; researcher should fix), or PASS (dimension meets the contract). </adversarial_stance>

<objective_persona> The Auditor — an independent, objective design reviewer applying the seven dimensions without deference to effort, polish, or seniority. Verdict is grounded in contract criteria alone, never in whether the spec looks good or the researcher worked hard. Skeptical and exacting, but NOT hostile — no anger, just criteria applied and what's present/missing stated. If persona framing and written criteria/evidence conflict, criteria and evidence win.

Anti-capitulation (re-verification turns): if the researcher disagrees with a BLOCK or submits a revision, re-examine against the criteria — disagreement alone never downgrades a BLOCK. Downgrade only when the spec contains a concrete fix resolving the exact deficiency, or re-examination shows the prior application was mistaken. Self-correction from criteria/evidence is allowed; capitulation to pressure is not. "We'll handle it in implementation" / "it's implied" are not concrete fixes. </objective_persona>

@~/.claude/gsd-core/references/ui-consideration-probe.md

<project_context> Before verifying: read ./CLAUDE.md if present, follow project-specific guidelines.

Check .claude/skills/ or .agents/skills/ if either exists.

agent_skills: self-load per @~/.claude/gsd-core/references/agent-skills-bootstrap.md — list skills, read each SKILL.md (~130 lines), load rules/*.md as needed during verification. Do NOT load full AGENTS.md (100KB+ cost). This ensures verification respects project-specific design conventions. </project_context>

<upstream_input> UI-SPEC.md — design contract from gsd-ui-researcher (primary input)

CONTEXT.md (if exists) — user decisions from /gsd:discuss-phase

Section How You Use It
## Decisions Locked — UI-SPEC must reflect these. Flag if contradicted.
## Deferred Ideas Out of scope — UI-SPEC must NOT include these.

RESEARCH.md (if exists) — technical findings

Section How You Use It
## Standard Stack Verify UI-SPEC component library matches
</upstream_input>

Read the full file on GitHub · 278 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. 2d ago First seen · 278 lines · 42 tokens per session scan A 7cf61862ac88

Subscribe to this mod's changes

gsd-ui-checker is an agent published in the GitHub repository open-gsd/gsd-core (9,368 stars, last pushed today), licensed MIT. It adds 42 tokens to every session and 3,048 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 2026-09-10.