Examine source code of ToolsTab

{
  "manifest_version": 3,
  "name": "ToolsTab",
  "version": "2.3",
  "description": "Minimal and responsive browser startpage with useful tools.",
  "chrome_url_overrides": {
    "newtab": "index.html"
  },
  "chrome_settings_overrides": {
    "homepage": "index.html"
  },
  "action": {
    "default_popup": "extension-popup/popup.html",
    "default_icon": {
      "128": "assets/icons/icon.png"
    }
  },
  "icons": {
    "128": "assets/icons/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "antoniopelusi2000@gmail.com"
    }
  }
}