# onsystem (npm · onsystem)

Catches palette colors, native elements and APIs your design system lacks in agent-written React.

- Trust score: 92/100 (high trust)
- Change this week: +29
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-11-06

## Components

- npm · `onsystem`: 92/100 (this document), [markdown](https://verifymcp.io/servers/dgesteves-onsystem/onsystem.md), [page](https://verifymcp.io/servers/dgesteves-onsystem/onsystem)

## Channel facts

- Registry: `npm`
- Package: `onsystem`
- Version: `0.12.1`
- Transport: `stdio`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically from public evidence about the published package, including repeated runs of it in an isolated sandbox, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-11-06.

- **Supply Chain Security**: 99/100
  - No malware found by supply-chain analysis.
  - No known CVEs affecting this package version or its production dependencies.
  - No install/post-install scripts declared.
  - 2 of 15 dependencies flagged as unhealthy.
- **Provenance & Transparency**: 100/100
  - Source repository is publicly reachable at the declared URL.
  - Cryptographically verified build provenance (signed, bound to dgesteves/onsystem).
  - Clear OSI-approved license (MIT).
  - Actively maintained (last published 6 days ago).
  - Publishes a security disclosure policy (SECURITY.md).
- **Schema Quality & AI Usability**: 75/100
  - 100% of prompts and resources have a non-trivial description (not blank, and not just the item's name).
  - AI-judged instruction clarity (good).
  - Context-footprint check failed: tool/resource definitions use about 1450 tokens (~241/item across 6 items; 5 tools + 1 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 80/100
  - Stability observed for 24 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% of tool parameters carry a description.
  - Structured output schemas are declared (100% of tools); any adoption earns full credit.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - We read all 5 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 7 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a current MCP spec version (2026-07-28).

## Install

### How do I install the onsystem MCP server?

onsystem runs locally as an npm package, launched with npx -y onsystem. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add dgesteves-onsystem -- npx -y onsystem
```

### Cursor

```json
{
  "mcpServers": {
    "dgesteves-onsystem": {
      "command": "npx",
      "args": [
        "-y",
        "onsystem"
      ]
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "dgesteves-onsystem": {
      "command": "npx",
      "args": [
        "-y",
        "onsystem"
      ]
    }
  }
}
```

### Codex

```bash
codex mcp add dgesteves-onsystem -- npx -y onsystem
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "dgesteves-onsystem": {
      "type": "local",
      "command": [
        "npx",
        "-y",
        "onsystem"
      ],
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add dgesteves-onsystem --command npx --arg -y --arg onsystem
```

### Hermes

```yaml
mcp_servers:
  dgesteves-onsystem:
    command: "npx"
    args: ["-y", "onsystem"]
```

### Netclaw

```json
{
  "McpServers": {
    "dgesteves-onsystem": {
      "Transport": "stdio",
      "Command": "npx",
      "Arguments": [
        "-y",
        "onsystem"
      ]
    }
  }
}
```

### Vellum

```bash
assistant mcp add dgesteves-onsystem -t stdio -c npx -a -y onsystem
```

### Other

```json
{
  "mcpServers": {
    "dgesteves-onsystem": {
      "command": "npx",
      "args": [
        "-y",
        "onsystem"
      ]
    }
  }
}
```

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-11-05 (score 92, +1)

No change was recorded against any check on this day. Stability & Change Management went from 73 to 77. That category is still filling its 30-day observation window: 22 days of observed history at the previous scan, 23 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-11-02 (score 91, +1)

No change was recorded against any check on this day. Stability & Change Management went from 63 to 67. That category is still filling its 30-day observation window: 19 days of observed history at the previous scan, 20 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-11-01 (score 90, +11)

- [security improvement] Known CVEs: unverified → pass
- [functional improvement] Dependency health: unverified → 0.94

### 2026-10-31 (score 79, +16)

- [security improvement] Malware scan: unverified → pass

### 2026-10-30 (score 63, −15)

- [security regression] Malware scan: pass → unverified
- [security improvement] Known CVEs: unverified → pass
- [functional improvement] Dependency health: unverified → 0.93
- [functional] Package version: 0.11.1 → 0.12.1
- [functional] Package version: 0.11.1 → 0.12.0
- [functional] Package version: 0.11.1 → 0.11.2

### 2026-10-29 (score 78, +5)

- [security regression] Known CVEs: pass → unverified
- [security regression] Stability: 0.50 → unverified
- [security regression] Tool safety: pass → unverified
- [security improvement] Malware scan: unverified → pass
- [functional regression] Dependency health: 0.93 → unverified
- [functional regression] Capabilities: pass → unverified
- [functional regression] Tool coverage: 100 → unverified
- [functional regression] Schema quality: 100 → unverified
- [functional] Package version: 0.10.3 → 0.11.1
- [functional] Package version: 0.10.3 → 0.11.0

### 2026-10-28 (score 73, 0)

- [security improvement] Malware scan: unverified → pass
- [functional] Package version: 0.10.1 → 0.10.3
- [functional] Package version: 0.10.1 → 0.10.2

### 2026-10-27 (score 73, −14)

- [security regression] Malware scan: pass → unverified
- [functional] Package version: 0.10.0 → 0.10.1

## MCP tools (5)

### `list_components` (~275 tokens)

List design-system 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. Call this before writing UI in this project. `query`, `kind` and `limit` narrow a long list. At a monorepo root, pass `path` for the project of the file you are editing; without it, every project is listed, each component with its package.

Input parameters:

- `kind` (string): "icon": only the components that render an <svg>, one by one. "component": all the others.
- `limit` (integer): Most components to list one by one.
- `path` (string): In a monorepo served from its root: the file you are editing, or a project folder, relative to the root, to answer from that project. Without it, every project is listed together. Ignored in a single…
- `query` (string): Only components with this text in their name, their parts' names or their description.

Output parameters:

- `components` (array): The components listed one by one, after `query`, `kind` and `limit`.
- `icons` (array): Without `kind`: icons, the components that render an <svg>, by name, five or more per module, or per folder for icons with a module each.
- `omitted` (integer): Matching components left out by `limit`.

### `get_component` (~196 tokens)

Get a component contract

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 a monorepo root, pass `path` (the file you are editing) to get the component its project uses.

Input parameters:

- `name` (string, required): Component name, e.g. "Button" or "CardHeader".
- `path` (string): In a monorepo served from its root: the file you are editing, or a project folder, relative to the root, to answer from that project. Without it, every project is listed together. Ignored in a single…

Output parameters:

- `aliases` (array)
- `classNames` (array)
- `compoundVariants` (array)
- `cssVars` (array)
- `defaultImport` (string): Another module that exports it as its default: "@mui/material/Button".
- `deprecated`
- `description` (string)
- `docs` (object)
- `element` (string): The native element it renders or wraps.
- `examples` (array)
- `exportName` (string)
- `import` (string): The import statement to use.
- `importPath` (string)
- `inherits` (array)
- `labelsChild` (object): A prop whose text is its child element's accessible name (MUI Tooltip's title), unless `unless` is set.
- `library` (string): The published package it is read from, by its type declarations: "@mui/material".
- `name` (string): How the component is written in JSX: Button, CardHeader, Tabs.List.
- `openProps` (boolean): Part of the props type did not resolve; extra props may be accepted.
- `package` (string): At a workspace root: the package its source belongs to, e.g. "@acme/ui".
- `parent` (string)
- `polymorphic` (string): A prop that renders another element or component in its place, with its props: "component".
- `projects` (array): At a workspace root: the folders of the projects that use it.
- `props` (array)
- `source` (object)
- `subcomponents` (array)
- `tokens` (array): Names of the design tokens its classes use.
- `variants` (array)

### `search_components` (~190 tokens)

Search components by intent

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`. Use it when you do not know which component fits.

Input parameters:

- `limit` (integer): Maximum results.
- `path` (string): In a monorepo served from its root: the file you are editing, or a project folder, relative to the root, to answer from that project. Without it, every project is listed together. Ignored in a single…
- `query` (string, required): What the UI should do, in plain words.

Output parameters:

- `results` (array)

### `get_tokens` (~198 tokens)

Get design 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 colors are listed under their own headings: they are for charts and the sidebar, not for status colors.

Input parameters:

- `category` (string): Only tokens of this category.
- `path` (string): In a monorepo served from its root: the file you are editing, or a project folder, relative to the root, to answer from that project. Without it, every project is listed together. Ignored in a single…
- `query` (string): Substring to match in names, usages or descriptions.

Output parameters:

- `tokens` (array)

### `check_ui` (~333 tokens)

Check UI code against the design system

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 id, a message and a suggested fix. Run it on every snippet or file you write and fix all errors. Pass `path` for a file in the project, or `code` for unsaved code, with `path` (or `filename`) naming the file it is for or its project folder.

Input parameters:

- `code` (string): TSX/JSX source to check (up to 1,000,000 characters).
- `filename` (string): Name to report `code` under; a .jsx extension parses it as JSX. At a monorepo root, the path the code will be saved under, which picks the project whose design system checks it. When the server was s…
- `limit` (integer): Most diagnostics to return, errors first (default 50). The counts and byRule cover all of them.
- `path` (string): Path of a .tsx, .jsx, .ts or .js file, relative to the project root (the monorepo root, when served from there) or absolute: the file to check, or, with `code`, the file the code is for, as `filename…

Output parameters:

- `byRule` (object): Every finding per rule, shown or not.
- `diagnostics` (array): Up to `limit` diagnostics, errors first; `omitted` says how many more there are.
- `errorCount` (integer)
- `file` (string)
- `notice` (string): Set when no components or no color tokens were found, so rules did not run, when components came from modules the model does not include, when the project depends on a component library onsystem does…
- `ok` (boolean): True when there are no errors.
- `omitted` (integer): Diagnostics left out by `limit`.
- `skipped` (string): Why the file was not checked: it renders an image (next/og) or an email, or the config's `exclude` leaves it out.
- `unchecked` (object): Components imported from modules the model does not include, not checked.
- `warningCount` (integer)

## Diagnostics

Captured diagnostic sections: Provenance, Dependencies. The full working is on the page: https://verifymcp.io/servers/dgesteves-onsystem/onsystem#diagnostics

## Score history

- 2026-11-06: 92
- 2026-11-05: 92
- 2026-11-04: 91
- 2026-11-03: 91
- 2026-11-02: 91
- 2026-11-01: 90
- 2026-10-31: 79
- 2026-10-30: 63
- 2026-10-29: 78
- 2026-10-28: 73
- 2026-10-27: 73
- 2026-10-26: 87
- 2026-10-25: 87
- 2026-10-24: 61
- 2026-10-23: 71
- 2026-10-22: 85
- 2026-10-21: 70
- 2026-10-20: 85
- 2026-10-19: 84
- 2026-10-18: 84
- 2026-10-17: 83
- 2026-10-16: 72
- 2026-10-15: 82
- 2026-10-14: 82
- 2026-10-13: 82
- 2026-10-12: 50

## Common questions

### What is the onsystem MCP server?

onsystem is an MCP server listed in the public MCP registry as io.github.dgesteves/onsystem. Catches palette colors, native elements and APIs your design system lacks in agent-written React. This page covers its npm package (onsystem).

### Is the onsystem MCP server safe to use?

onsystem scores 92 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 6 November 2026. It declares no install or post-install scripts. Its build provenance is signed and verified. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the onsystem MCP server expose?

onsystem exposes 5 tools: list_components, get_component, search_components, get_tokens, check_ui. Their descriptions and schemas cost roughly 1,192 tokens of context every time the server is loaded.

### Is the onsystem MCP server still maintained?

onsystem is still listed as active in the MCP registry. We last reached this channel on 6 November 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

### What licence is the onsystem MCP server under?

onsystem declares the MIT licence, which is OSI-approved. That covers the source only, and says nothing about the cost of any service it calls.

### What did VerifyMCP test on the onsystem MCP server?

VerifyMCP ran 16 checks on onsystem, covering Malware scan, Known CVEs, Install scripts, Dependency health and 12 more. Endpoint Security and Transport & Reachability do not apply to an npm package, so they were not tested. The score does not measure everything, and the scoring documentation lists what it leaves out.

## Links

- npm package: https://www.npmjs.com/package/onsystem
- Socket report: https://socket.dev/npm/package/onsystem
- Repository: https://github.com/dgesteves/onsystem
- Website: https://onsystem.vercel.app/
- Changelog RSS feed: https://verifymcp.io/servers/dgesteves-onsystem/onsystem.xml
- Changelog JSON feed: https://verifymcp.io/servers/dgesteves-onsystem/onsystem/changelog.json
- Trust report (JSON): https://verifymcp.io/servers/dgesteves-onsystem/onsystem.json
- HTML version of this page: https://verifymcp.io/servers/dgesteves-onsystem/onsystem