Onsystem MCP Server

by dgesteves• 165•• Scanned•Claim this listing•Request removal

Design & Mediaaccessibilityagent guardrailsai agentsclaude codeclaude code plugin

Keeps coding agents on your design system: catches palette colors, native elements and APIs your system lacks, at every edit and pull request, with the fix. Set it up once in your design-system package; every app in your monorepo gets it.

Onsystem is an open-source mcp server by dgesteves, written mainly in TypeScript, with 165 GitHub stars and the MIT license. Its code was last updated Oct 30, 2026. The latest npm release is onsystem 0.12.1, published Oct 30, 2026, with 211 downloads last week.

Scan summary: scanned Nov 5, 2026 at commit 6425861. Seen able to read environment and secrets, connect to the internet. Scan policy

about README security reviews

How to install Onsystem

Built from the start command in the project's README: npx -y onsystem check . # the same check the agent and CI run. Check the README for required keys or settings.

Claude Code · Terminal

claude mcp add onsystem -- npx -y onsystem check .   # the same check the agent and CI run

Claude Desktop · claude_desktop_config.json

{
  "mcpServers": {
    "onsystem": {
      "command": "npx",
      "args": [
        "-y",
        "onsystem",
        "check",
        ".",
        "#",
        "the",
        "same",
        "check",
        "the",
        "agent",
        "and",
        "CI",
        "run"
      ]
    }
  }
}

Cursor · .cursor/mcp.json

{
  "mcpServers": {
    "onsystem": {
      "command": "npx",
      "args": [
        "-y",
        "onsystem",
        "check",
        ".",
        "#",
        "the",
        "same",
        "check",
        "the",
        "agent",
        "and",
        "CI",
        "run"
      ]
    }
  }
}

VS Code · Terminal

code --add-mcp '{"name":"onsystem","command":"npx","args":["-y","onsystem","check",".","#","the","same","check","the","agent","and","CI","run"]}'

What Onsystem can touch

Run shell commandsNot seen in this scan
Run dynamic codeNot seen in this scan
Read or write filesNot seen in this scan
Read environment and secretsFound in the code by our scan
Control a web browserNot seen in this scan
Connect to databasesNot seen in this scan
Read or send messagesNot seen in this scan
Touch money or tradingNot seen in this scan
Connect to the internetFound in the code by our scan

"Not seen" means our checks did not find it, and the tool may still do it. Covers commit 6425861, Nov 5, 2026. See the scan policy.

Before you install Onsystem

AgenticMart scanned Onsystem on Nov 5, 2026 with automated checks for hidden code, known-malicious packages, leaked secrets and vulnerable dependencies. The result covers one commit under our scan policy, so review what access you give it and check any advisories shown here.

What it can access

An MCP server is a program your AI app starts and talks to. A local one runs with your user's permissions: it can see the files, environment variables and network your account can.

Before you install

Pin the version you reviewed instead of always installing the latest release.
Read the tool list or scripts before the first run, and keep approval prompts on for actions that write, send or delete.

Maintained by dgesteves on GitHub, 165 stars and 4 forks. Popularity is not proof of safety.
Last code change: Oct 30, 2026.
Open-source license: MIT.

Read the scan report What our scan checks

Tools Onsystem exposes (5)

Listed by the server itself during our scan of commit 6425861.

list_components
List every component in the project design system with a one-line description, the native element it renders, its variant values, its parts and its import. Icons (components that render an <svg>) are named on one line per import, or per folder for icons with a module each, five or more to a line. Ca
get_component
Get the full contract of one component: import, props with types and defaults, cva variants and the classes each applies, parts (sub-components), design tokens it uses, usage guidelines and examples from its docs. Call it before using a component. Accepts "Button", "CardHeader" or "Card.Header". At
search_components
Find components by what you want to build, e.g. "confirm a destructive action", "status label", "text field with validation". Ranks names, descriptions, docs, props and variant values with BM25 (local, no API key). When no component clearly matches, it says so and lists the nearest, marked `weak`. U
get_tokens
List design tokens with resolved values, dark-mode values and how to use each (Tailwind class or CSS variable). Filter by category (color, spacing, radius, typography, shadow, other) or a substring. Use these instead of hex codes, px values or Tailwind default palette classes. Chart and sidebar colo
check_ui
Lint TSX/JSX against the design system. Reports hardcoded colors, spacing and radius (with the nearest token), native elements that have a design-system component, unknown components, props and variant values, and icon-only buttons without an accessible name. Each diagnostic has line/column, a rule

Onsystem is an open-source mcp server by dgesteves, written mainly in TypeScript. Keeps coding agents on your design system: catches palette colors, native elements and APIs your system lacks, at every edit and pull request, with the fix. Set it up once in your design-system package; every app in your monorepo gets it.

At a glance

Stars: 165
Forks: 4
Language: TypeScript
License: MIT
Created: Oct 2026
Last update: Oct 30, 2026
Type: MCP Server
Price: Free

Topics

accessibilityagent-guardrailsai-agentsclaude-codeclaude-code-plugincursordesign-systemdesign-system-lintdesign-tokenslintermcpmcp-servermodel-context-protocolreactshadcn-uitailwindcsstypescript

Questions about Onsystem

What is Onsystem?

Who maintains Onsystem?

Onsystem is maintained by dgesteves on GitHub (dgesteves/onsystem). AgenticMart lists it from public repository data.

Is Onsystem safe to use?

What license does Onsystem use?

It is published under the MIT license.

Guides

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