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 skills add 21st-dev/skill --skill 21st-cli-usegit clone --depth 1 https://github.com/21st-dev/skillWrote 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.
[](https://agentmods.dev/skills/21st-dev/skill/21st-cli-use)<a href="https://agentmods.dev/skills/21st-dev/skill/21st-cli-use"><img src="https://agentmods.dev/badge/skills/21st-dev/skill/21st-cli-use/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.
<a href="https://agentmods.dev/skills/21st-dev/skill/21st-cli-use"><img src="https://agentmods.dev/badge/skills/21st-dev/skill/21st-cli-use.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk warn
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00160 | $0.01322 |
| Opus 5.5 | $0.00064 | $0.00529 |
| Sonnet 5.5 | $0.00032 | $0.00264 |
| Haiku 4.5 | $0.00016 | $0.00132 |
Grade A, and why
21st-cli-use scanned grade A with 1 finding 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 1mo 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
Prints each logo's name and SVG url(s) to curl straight into a project. Uses the Copies of this mod
2 near-identical copies found in the catalogue:
- 21st-cli-use — 100% identical, 0 lines differ
- 21st-cli-use — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 129 lines — stays where its author put it; the contents beside it link to each section on GitHub.
21st CLI — find, install & generate from the terminal
The 21st CLI (npx @21st-dev/cli, bin 21st) is the command-line surface for
the 21st.dev catalog. Search first, install what fits, and only hand-write UI
when nothing matches. To publish your own components/themes/templates, use
the 21st-registry skill; to publish a project's design as a theme, use
21st-design-sync.
Auth (do this once)
Two interchangeable credentials, both sent as the API key:
- Login session —
npx @21st-dev/cli loginopens the browser and saves a token to~/.config/21st/auth.json. Best for interactive/dev machines. - API key —
21st_sk_…from https://21st.dev/mcp (or https://21st.dev/settings/api-keys). Pass via--api-key <key>or theTWENTYFIRST_TOKEN/API_KEY_21STenv var. Best for CI.
21st whoami shows the signed-in account; 21st usage shows retrieval
tier/quota and the 21st AI generation status, not an AI credit balance.
For structured status, use MCP get_usage.aiGenerationEnabled or CLI 1.17.1+
21st usage --json. Missing or unknown status does not grant AI access. 21st logout
clears the saved login.
Metering
Metadata (search, previews, a theme's CSS) is free. Retrieving component
code (21st get, install) has a free daily quota; Builder includes
unlimited retrieval. Hosted 21st AI requires separate AI access and consumes
AI credits. Base Builder has AI off. Check 21st usage before choosing
generation: when AI is not explicitly enabled, search and retrieve code,
then adapt it with your own coding agent. Do not retry a generation denied
with ai_subscription_required until AI access is enabled.
Find
# Search everything (components + themes + templates)
21st search "pricing table" --limit 10
21st search button --type c # components only (c | theme | template)
21st search dark --type theme
# Filters: --tag <slug> --color <bucket> --sort <s> --free|--paid
# --author <username> --mine --liked --json for machine output
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.
- 1mo ago Changed · +7 lines 88ff054abb43
- 1mo ago First seen · 122 lines · 160 tokens per session scan A c888765e0640
21st-cli-use is a skill published in the GitHub repository 21st-dev/skill (20 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 160 tokens to every session and 1,322 once invoked, about $0.0006 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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