{
  "descriptorVersion": "1.0.0",
  "name": "calculate_transport_subsidy",
  "title": "Public transport fare subsidy calculator",
  "description": "Estimate Hong Kong's Public Transport Fare Subsidy for one month on this page, using the page's own calculation (HK$500 threshold, one-third of the excess, HK$400 monthly cap). Replaces the page's spending input and shows the same result on screen. An estimate, not the scheme's official record. Calculation or source matching runs in this page; arguments and results are not uploaded to Agoodeal servers or to Google Analytics, and the result is returned only to the calling agent. Non-sensitive usage metadata (tool name, outcome, execution mode, error code, duration; predefined source IDs for source matching) is reported through the site’s existing Google Analytics 4.",
  "execution": {
    "environment": "browser",
    "interface": "WebMCP imperative API: document.modelContext.registerTool (experimental)",
    "executionMode": "local_calculation",
    "pageUrls": [
      "https://www.agoodeal.com/tools/public-transport-subsidy-calculator/"
    ],
    "requirement": "Open one of pageUrls in a browser that exposes document.modelContext. As of October 2026 this is experimental: Chrome 149+ with chrome://flags/#enable-webmcp-testing, or an origin trial that Agoodeal has not joined. Without it the page works normally for people and no tool is registered.",
    "serverEndpoint": null,
    "argumentsEncoding": "JSON object (some browser versions require callers to pass it as a JSON string).",
    "returns": "A JSON string matching outputSchema."
  },
  "annotations": {
    "readOnlyHint": false,
    "untrustedContentHint": false,
    "consequentialHint": false
  },
  "annotationNotes": "readOnlyHint is false because the tool replaces every input on the page and shows the same result the visitor would see. It submits, stores and books nothing.",
  "inputSchema": {
    "type": "object",
    "additionalProperties": false,
    "required": [
      "monthlySpend"
    ],
    "properties": {
      "monthlySpend": {
        "type": "number",
        "minimum": 0,
        "description": "Eligible monthly public transport spending in HK$ under the Public Transport Fare Subsidy Scheme."
      }
    }
  },
  "outputSchema": {
    "oneOf": [
      {
        "type": "object",
        "required": [
          "ok",
          "tool",
          "mode",
          "arguments",
          "result",
          "rendered",
          "uiInputsReplaced"
        ],
        "properties": {
          "ok": {
            "const": true
          },
          "tool": {
            "type": "string"
          },
          "mode": {
            "const": "local_calculation"
          },
          "arguments": {
            "type": "object"
          },
          "result": {
            "type": "object"
          },
          "rendered": {
            "type": "object",
            "description": "Text the page displayed after the same calculation, keyed by element id."
          },
          "uiInputsReplaced": {
            "const": true
          },
          "notes": {
            "type": "array",
            "items": {
              "type": "string"
            }
          }
        }
      },
      {
        "type": "object",
        "required": [
          "ok",
          "error"
        ],
        "properties": {
          "ok": {
            "const": false
          },
          "error": {
            "type": "object",
            "required": [
              "code",
              "message"
            ],
            "properties": {
              "code": {
                "enum": [
                  "invalid_json",
                  "invalid_argument",
                  "missing_argument",
                  "unknown_argument",
                  "out_of_range",
                  "internal_error"
                ]
              },
              "message": {
                "type": "string"
              },
              "field": {
                "type": "string"
              }
            }
          }
        }
      }
    ]
  },
  "privacy": "Uses only the arguments supplied: every relevant page input is replaced (omitted optional arguments clear their field), so earlier visitor input is never read into the result. Nothing is stored. Calculation or source matching runs in this page; arguments and results are not uploaded to Agoodeal servers or to Google Analytics, and the result is returned only to the calling agent. Non-sensitive usage metadata (tool name, outcome, execution mode, error code, duration; predefined source IDs for source matching) is reported through the site’s existing Google Analytics 4.",
  "coverage": "Rules effective 1 June 2025: HK$500 threshold, one-third of the excess, HK$400 cap.",
  "limits": [
    "Estimate only; the scheme system records are final."
  ],
  "officialSources": [
    {
      "id": "ptfss-calculation",
      "name": "公共交通費用補貼計劃：計算補貼",
      "publisher": "Transport Department (PTFSS)",
      "kind": "web_page",
      "url": "https://www.ptfss.gov.hk/tc-main.html#/tc-ope-01"
    },
    {
      "id": "gov-ptfss-threshold-2025",
      "name": "政府新聞公報：2025年6月1日起的門檻",
      "publisher": "Hong Kong Government",
      "kind": "web_page",
      "url": "https://www.info.gov.hk/gia/general/202505/26/P2025052600290.htm"
    }
  ],
  "agoodealPage": "https://www.agoodeal.com/tools/public-transport-subsidy-calculator/"
}