A remotely hosted MCP server from 21st.dev. It connects through an HTTP endpoint and requires an API key.

Use it when an agent needs to call 21st.dev through MCP. The provided details do not say which specific operations it supports.

It gives an MCP-compatible coding agent access to the service exposed by 21st.dev without running that server locally.

21st — MCP server by PsYcGoD/sage

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/PsYcGoD/sage

Made for: Claude Code, Codex, Cursor, Gemini CLI, OpenCode.

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.

README.md

[![agentmods](https://agentmods.dev/badge/mcp/psycgod/sage/21st/github.svg)](https://agentmods.dev/mcp/psycgod/sage/21st)

Your own site

<a href="https://agentmods.dev/mcp/psycgod/sage/21st"><img src="https://agentmods.dev/badge/mcp/psycgod/sage/21st/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.

Your own site · 80×15

<a href="https://agentmods.dev/mcp/psycgod/sage/21st"><img src="https://agentmods.dev/badge/mcp/psycgod/sage/21st.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session not measured What this adds to a session before it is invoked.

When invoked not measured Not applicable: nothing here is loaded into a session.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin 100% copy Near-identical to another mod in the catalogue.

Security

Grade A, and why

21st 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 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.

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

100% identical to 21st — 0 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.

.mcp.json · 9 lines

What it actually says

{
  "21st": {
    "type": "http",
    "url": "https://21st.dev/api/mcp",
    "headers": {
      "x-api-key": "${API_KEY_21ST}"
    }
  }
}

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.

1mo ago First seen · 9 lines scan A 89c04e6b12c5

Subscribe to this mod's changes

21st is an MCP server published in the GitHub repository PsYcGoD/sage (11 stars, last pushed 1mo ago), licensed MIT. Its token cost is not measured: an MCP server costs its tool schemas, not its config file. A static security scan graded it A with 0 findings. It is 100% identical to 21st, differing in 0 lines, and is treated as a copy.

DevOps and cloud ai-agents automation cli command-line developer-tools

21st

Getting it into your agent

Wrote this? Show the measurements

Grade A, and why

Nothing flagged

This is a copy

What it actually says

What this file has done since we first saw it

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