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.
npx agentmods add skills/21st-dev/claude-code-plugin/21st-ui-explorenpx skills add 21st-dev/claude-code-plugin --skill 21st-ui-exploregit clone --depth 1 https://github.com/21st-dev/claude-code-pluginWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00098 | $0.00450 |
| Opus 5 | $0.00049 | $0.00225 |
| Sonnet 5 | $0.00020 | $0.00090 |
| Haiku 4.5 | $0.00010 | $0.00045 |
Grade A, and why
21st-ui-explore 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.
Copies of this mod
2 near-identical copies found in the catalogue:
- 21st-ui-explore — 100% identical, 0 lines differ
- 21st-ui-explore — 100% identical, 0 lines differ
What it actually says
Explore grounded UI directions
Create real choices without abandoning the project's visual identity.
Workflow
-
Read
.21st/design.jsonand the relevant product UI. If context is missing, run21st init --design-context. -
Search 21st for multiple relevant references before generating:
21st search "<interface and product context>" --context auto -
Define three named directions. Each direction must differ on at least two meaningful axes such as hierarchy, information density, navigation model, content emphasis, interaction pattern, or composition. Color-only variants do not count.
-
Keep shared constraints fixed: real stack, tokens, brand assets, required content, accessibility, and responsive behavior.
-
Generate or implement comparable previews. Prefer:
21st generate "<goal plus fixed constraints>" --context auto --variants 3 -
Present the options together when the host supports a picker. Otherwise give each option a preview/deep link and a compact comparison.
-
Recommend one direction with concrete tradeoffs, but let the user choose.
-
After selection, remove abandoned local variants and record the decision in
.21st/design.json.
Direction contract
For every direction provide:
- a short, descriptive name;
- the core idea and intended user effect;
- the 21st/project references used;
- what stays consistent with the project;
- two or more meaningful differences;
- accessibility or responsive risks;
- the best-fit scenario.
Do not generate random style mutations. Every difference must support a product or usability hypothesis that a user can evaluate.
What ships with it
1 file 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.
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.
- 2d ago First seen · 52 lines · 98 tokens per session scan A 4482d001cfe8
21st-ui-explore is a skill published in the GitHub repository 21st-dev/claude-code-plugin (7 stars, last pushed 6d ago), licensed Apache-2.0. It adds 98 tokens to every session and 450 once invoked, about $0.0005 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 2026-08-31.
Other skills, from other repositories
systematic-debugging
Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.
next-cache-components-adoption
Turn on Cache Components in a Next.js app and resolve the blocking routes it surfaces. Use when the user wants to enable, adopt, or migrate to Cache Components, flip the cacheComponents flag, work through a flood of blocking-prerender / instant validation errors, run the cache-components-instant-false codemod, or…
babysit-pr
Babysit a GitHub pull request after creation by continuously polling review comments, CI checks/workflow runs, and mergeability state until the PR is merged/closed or user help is required. Diagnose failures, retry likely flaky failures up to 3 times, auto-fix/push branch-related issues when appropriate, and keep…
imagegen
Generate or edit raster images when the task benefits from AI-created bitmap visuals such as photos, illustrations, textures, sprites, mockups, or transparent-background cutouts. Use when Codex should create a brand-new image, transform an existing image, or derive visual variants from references, and the output…
cpu-profile-analysis
Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…
next-cache-components-optimizer
Drive a Next.js route to instant navigation by setting up an agentic loop, under Cache Components / PPR, on initial load (hard navigation) and client-side navigation (soft navigation). Encode the goal as a failing @next/playwright instant() e2e and work it to green, one verified route at a time; the shipped test then…