What is api-development?

Python rules for building clients for Japan’s real-estate information API, a service that provides property and geographic data.

Use them to build API wrappers, support JSON, GeoJSON, and vector-tile responses, map Japanese fields, handle retries, and test endpoints and failures.

They define consistent handling for secure requests, API keys, formats, errors, data models, geographic data, and tests.

api-development — Cursor rule for Cursor by koizumikento: Python rules for building clients for Japan’s real-estate information…

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods

npx agentmods add rules/koizumikento/reinfolib-mcp/api-development

Clone the repo

git clone --depth 1 https://github.com/koizumikento/reinfolib-mcp

Made for: Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/rules/koizumikento/reinfolib-mcp/api-development.svg)](https://agentmods.dev/rules/koizumikento/reinfolib-mcp/api-development)

Your own site

<a href="https://agentmods.dev/rules/koizumikento/reinfolib-mcp/api-development"><img src="https://agentmods.dev/badge/rules/koizumikento/reinfolib-mcp/api-development.svg" alt="Measured on agentmods" height="20"></a>

Per session 0 Nothing until a file matches its globs; then the whole rule loads.

When invoked 677 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5	$0.00000	$0.00677
Opus 5	$0.00000	$0.00338
Sonnet 5	$0.00000	$0.00135
Haiku 4.5	$0.00000	$0.00068

Measured 4d ago against content hash 8f0ad81ebc44, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-development scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/api-development.mdc · 85 lines

What it actually says

不動産情報ライブラリAPI開発規則

APIクライアント開発ガイドライン

1. HTTPSリクエスト処理

全てのAPIリクエストはHTTPSプロトコルを使用
APIキーはHTTPヘッダー Ocp-Apim-Subscription-Key で送信
リクエストタイムアウトとリトライ機能を実装

2. レスポンス形式対応

# サポートする出力形式
SUPPORTED_FORMATS = {
    'json': 'application/json',
    'geojson': 'application/geo+json', 
    'pbf': 'application/x-protobuf'  # バイナリベクトルタイル
}

3. エラーハンドリング

APIキー未設定エラー
レート制限エラー
データ形式エラー
ネットワークエラー

4. データモデル定義

Pydanticを使用したタイプセーフなデータモデル
GeoJSONオブジェクトの適切な型定義
日本語フィールド名の英語マッピング

5. APIクライアントラッパー設計

参照: client-library.mdc

# ラッパークラスを使用した設計
from reinfolib_mcp import ReinfiolibClient

# APIキー直接指定
client = ReinfiolibClient(api_key="your_api_key")

# 環境変数から自動取得
client = ReinfiolibClient()  # REINFOLIB_API_KEY環境変数を使用

6. API URL パターン

BASE_URL = "https://www.reinfolib.mlit.go.jp/ex-api/external"

# APIエンドポイント例
ENDPOINTS = {
    "real_estate_price": "/XIT001",  # 不動産価格情報
    "municipalities": "/XIT002",      # 市区町村一覧
    "appraisal_info": "/XIT003",     # 鑑定評価書情報
    # ... 他のエンドポイント
}

7. 地理空間データ処理

GeoJSONオブジェクトの適切な処理
座標系の変換対応（JGD2011等）
バイナリベクトルタイルのデコード

8. ユニットテスト

モックレスポンスを使用したテスト
全APIエンドポイントのテストカバレッジ
エラーケースのテスト

9. 非同期処理

asyncio/aiohttpを使用した非同期APIクライアント
複数APIの並行呼び出し対応

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

4d ago First seen · 85 lines · 677 tokens per session scan A 8f0ad81ebc44

Subscribe to this mod's changes

api-development is a cursor rule published in the GitHub repository koizumikento/reinfolib-mcp (2 stars, last pushed 8d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 677 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Backend and APIs Languages Python japan mcp mlit model-context-protocol public-data

api-development