# io.github.easonwong-de/firefox-css-theme (npm · firefox-css-theme)

MCP for building, inspecting, and live-debugging Firefox CSS themes.

- Trust score: 89/100 (high trust)
- Change this week: +4
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-09-20

## Components

- npm · `firefox-css-theme`: 89/100 (this document), [markdown](https://verifymcp.io/servers/easonwong-de-firefox-css-theme/firefox-css-theme.md), [page](https://verifymcp.io/servers/easonwong-de-firefox-css-theme/firefox-css-theme)

## Channel facts

- Registry: `npm`
- Package: `firefox-css-theme`
- Version: `0.2.8`
- 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 2026-09-20.

- **Supply Chain Security**: 98/100
  - No malware found by supply-chain analysis.
  - No known CVEs affecting this package version or its production dependencies.
  - No install/post-install scripts declared.
  - 44 of 131 dependencies flagged as unhealthy.
- **Provenance & Transparency**: 97/100
  - Source repository is publicly reachable at the declared URL.
  - Cryptographically verified build provenance (signed, bound to easonwong-de/Firefox-CSS-Theme).
  - Clear OSI-approved license (MIT).
  - Actively maintained (last published 15 days ago).
  - Disclosure check failed: no security disclosure policy was found in the source repository.
- **Schema Quality & AI Usability**: 80/100
  - AI-judged instruction clarity (excellent).
  - Tool/resource definitions use about 527 tokens (~47/item across 11 items; 11 tools + 0 resources), lean.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 63/100
  - Stability observed for 19 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.
- **Tool Safety**: 75/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - 0 of 2 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation; "remove_theme_css" implies "remove" and declares no destructiveHint at all, which the MCP spec reads as destructive by default.
  - An AI judge read all 11 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.

## Install

### How do I install the io.github.easonwong-de/firefox-css-theme MCP server?

io.github.easonwong-de/firefox-css-theme runs locally as an npm package, launched with npx -y firefox-css-theme. 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 easonwong-de-firefox-css-theme -- npx -y firefox-css-theme
```

### Cursor

```json
{
  "mcpServers": {
    "easonwong-de-firefox-css-theme": {
      "command": "npx",
      "args": [
        "-y",
        "firefox-css-theme"
      ]
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "easonwong-de-firefox-css-theme": {
      "command": "npx",
      "args": [
        "-y",
        "firefox-css-theme"
      ]
    }
  }
}
```

### Codex

```bash
codex mcp add easonwong-de-firefox-css-theme -- npx -y firefox-css-theme
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "easonwong-de-firefox-css-theme": {
      "type": "local",
      "command": [
        "npx",
        "-y",
        "firefox-css-theme"
      ],
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add easonwong-de-firefox-css-theme --command npx --arg -y --arg firefox-css-theme
```

### Hermes

```yaml
mcp_servers:
  easonwong-de-firefox-css-theme:
    command: "npx"
    args: ["-y", "firefox-css-theme"]
```

### Netclaw

```json
{
  "McpServers": {
    "easonwong-de-firefox-css-theme": {
      "Transport": "stdio",
      "Command": "npx",
      "Arguments": [
        "-y",
        "firefox-css-theme"
      ]
    }
  }
}
```

### Vellum

```bash
assistant mcp add easonwong-de-firefox-css-theme -t stdio -c npx -a -y firefox-css-theme
```

### Other

```json
{
  "mcpServers": {
    "easonwong-de-firefox-css-theme": {
      "command": "npx",
      "args": [
        "-y",
        "firefox-css-theme"
      ]
    }
  }
}
```

## 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.

### 2026-09-20 (score 89, +1)

No change was recorded against any check on this day. Stability & Change Management went from 60 to 63. That category is still filling its 30-day observation window: 18 days of observed history at the previous scan, 19 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-18 (score 88, +1)

No change was recorded against any check on this day. Stability & Change Management went from 53 to 57. That category is still filling its 30-day observation window: 16 days of observed history at the previous scan, 17 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-16 (score 87, +1)

No change was recorded against any check on this day. Stability & Change Management went from 47 to 50. That category is still filling its 30-day observation window: 14 days of observed history at the previous scan, 15 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-14 (score 86, +1)

No change was recorded against any check on this day. Stability & Change Management went from 40 to 43. That category is still filling its 30-day observation window: 12 days of observed history at the previous scan, 13 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-12 (score 85, +1)

No change was recorded against any check on this day. Stability & Change Management went from 33 to 37. That category is still filling its 30-day observation window: 10 days of observed history at the previous scan, 11 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-10 (score 84, +1)

No change was recorded against any check on this day. Stability & Change Management went from 27 to 30. That category is still filling its 30-day observation window: 8 days of observed history at the previous scan, 9 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-07 (score 83, +1)

No change was recorded against any check on this day. Stability & Change Management went from 17 to 20. That category is still filling its 30-day observation window: 5 days of observed history at the previous scan, 6 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-06 (score 82, +11)

- [security improvement] Known CVEs: unverified → pass
- [functional improvement] Dependency health: unverified → 0.86

## MCP tools (11)

### `launch_browser` (~88 tokens)

Launch a Firefox instance with chrome debugging capabilities enabled.

Input parameters:

- `binaryPath` (string): Optional path to Firefox executable binary.
- `headless` (boolean): Optional flag to run Firefox in headless mode.
- `novaUi` (boolean): Optional flag to enable Firefox Nova UI preferences.
- `profileName` (string): Optional name of existing Firefox profile. If omitted, uses an isolated temporary profile.

### `close_browser` (~14 tokens)

Close the running Firefox instance.

### `customize_toolbar` (~47 tokens)

Activate or manage the Firefox Customise Toolbar mode in the browser chrome.

Input parameters:

- `action` (string): Action to perform on customise toolbar mode ('enter' or 'exit'). Defaults to 'enter'.

### `get_ui_tree` (~48 tokens)

Retrieve the hierarchical DOM tree of the Firefox chrome user interface window.

Input parameters:

- `maxDepth` (number): Maximum recursive depth to traverse.
- `rootSelector` (string): CSS selector for root element.

### `query_ui_elements` (~47 tokens)

Find elements in the Firefox UI chrome document matching a CSS selector.

Input parameters:

- `selector` (string, required): CSS selector to query in chrome document (e.g. '#nav-bar', '#TabsToolbar').

### `get_computed_styles` (~56 tokens)

Extract computed CSS properties for a Firefox UI chrome element.

Input parameters:

- `properties` (array): Optional list of specific CSS property names.
- `selector` (string, required): CSS selector of the UI element (e.g. '#urlbar-background').

### `inject_theme_css` (~62 tokens)

Inject or replace a live stylesheet in the Firefox window.

Input parameters:

- `css` (string, required): CSS rules to inject.
- `id` (string): Identifier for the style.
- `target` (string, required): Target scope: chrome for browser UI, or content for web pages.

### `remove_theme_css` (~49 tokens)

Remove an injected stylesheet from the Firefox window.

Input parameters:

- `id` (string, required): Identifier of the style to remove.
- `target` (string, required): Target scope of the style to remove: chrome or content.

### `list_theme_css` (~36 tokens)

List all custom stylesheets currently injected in the Firefox window.

Input parameters:

- `target` (string, required): Target scope to list: chrome or content.

### `take_ui_screenshot` (~41 tokens)

Capture a PNG screenshot of the Firefox browser chrome window or a specific UI component.

Input parameters:

- `selector` (string): Optional CSS selector to screenshot a specific element.

### `execute_chrome_javascript` (~39 tokens)

Execute privileged JavaScript code in the Firefox chrome window context.

Input parameters:

- `script` (string, required): JavaScript code string to evaluate in chrome context.

## Diagnostics

Captured diagnostic sections: Provenance, Dependencies. The full working is on the page: https://verifymcp.io/servers/easonwong-de-firefox-css-theme/firefox-css-theme#diagnostics

## Score history

- 2026-09-20: 89
- 2026-09-19: 88
- 2026-09-18: 88
- 2026-09-17: 87
- 2026-09-16: 87
- 2026-09-15: 86
- 2026-09-14: 86
- 2026-09-13: 85
- 2026-09-12: 85
- 2026-09-11: 84
- 2026-09-10: 84
- 2026-09-09: 83
- 2026-09-08: 83
- 2026-09-07: 83
- 2026-09-06: 82
- 2026-09-05: 71
- 2026-09-04: 80
- 2026-09-03: 80
- 2026-09-02: 80
- 2026-09-01: 80

## Common questions

### What is the io.github.easonwong-de/firefox-css-theme MCP server?

io.github.easonwong-de/firefox-css-theme is an MCP server listed in the public MCP registry as io.github.easonwong-de/firefox-css-theme. MCP for building, inspecting, and live-debugging Firefox CSS themes. This page covers its npm package (firefox-css-theme).

### Is the io.github.easonwong-de/firefox-css-theme MCP server safe to use?

io.github.easonwong-de/firefox-css-theme scores 89 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 20 September 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 io.github.easonwong-de/firefox-css-theme MCP server expose?

io.github.easonwong-de/firefox-css-theme exposes 11 tools: launch_browser, close_browser, customize_toolbar, get_ui_tree, query_ui_elements, and 6 more. Their descriptions and schemas cost roughly 527 tokens of context every time the server is loaded.

### Is the io.github.easonwong-de/firefox-css-theme MCP server still maintained?

io.github.easonwong-de/firefox-css-theme is still listed as active in the MCP registry. We last reached this channel on 20 September 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 io.github.easonwong-de/firefox-css-theme MCP server under?

io.github.easonwong-de/firefox-css-theme declares the MIT licence, which is OSI-approved. That covers the source only, and says nothing about the cost of any service it calls.

## Links

- npm package: https://www.npmjs.com/package/firefox-css-theme
- Socket report: https://socket.dev/npm/package/firefox-css-theme
- Repository: https://github.com/easonwong-de/Firefox-CSS-Theme
- Changelog RSS feed: https://verifymcp.io/servers/easonwong-de-firefox-css-theme/firefox-css-theme.xml
- Changelog JSON feed: https://verifymcp.io/servers/easonwong-de-firefox-css-theme/firefox-css-theme.json
- HTML version of this page: https://verifymcp.io/servers/easonwong-de-firefox-css-theme/firefox-css-theme