Lease Safe MCP

Lease Safe(전월세안전내비) is a PlayMCP-compatible remote MCP server for Korean lease, jeonse, wolse, and moving-safety guidance.

It uses official public data and reviewed official guidance to help users:

• run a one-shot lease safety assessment that combines rent market, sale market, red flags, and next actions
• convert a region name into official legal-dong codes through the official legal-dong API
• compare nearby reported rent deposits when a data.go.kr API key is configured
• compare a deposit against nearby sale prices to estimate sale-price-to-deposit risk
• detect contract red flags without making legal conclusions
• plan move-in protection steps such as move-in report, fixed date, and lease report
• prepare questions for landlords, agents, and official institutions
• route users to Government24, RTMS, Internet Registry Office, HUG, and lease dispute mediation paths
• summarize common lease-dispute prevention steps

PlayMCP Fit

• Streamable HTTP transport: POST /mcp
• Stateless server
• Tool count: 10
• No kakao string in server or tool names
• Required tool annotations included
• Compact Korean markdown outputs
• Dockerfile included for PlayMCP in KC Git source build
• GitHub Actions CI runs secret scan, tests, PlayMCP validation, local MCP HTTP smoke, MCP boundary rejection smoke, rate-limit smoke, production dependency audit, Docker build, and Docker runtime smoke

Data Sources

Automatic data:

• 행정안전부 행정표준코드 법정동코드 OpenAPI
• 국토교통부 아파트, 연립다세대, 단독/다가구, 오피스텔 전월세 실거래가 OpenAPI
• 국토교통부 아파트, 연립다세대, 단독/다가구, 오피스텔 매매 실거래가 OpenAPI

Reviewed official guidance:

• 정부24
• 부동산거래관리시스템 RTMS
• 인터넷등기소
• 법제처 찾기쉬운 생활법령
• 국가법령정보센터
• 한국부동산원·LH 임대차분쟁조정위원회
• HUG 주택도시보증공사
• 국세청
• 위택스

DATA_GO_KR_SERVICE_KEY is required for API-backed tools: assess_lease_safety, resolve_legal_dong_code, compare_rent_market, and compare_deposit_to_sale_market. Encoded and decoded data.go.kr keys are both accepted. Missing keys, placeholder values, whitespace, malformed percent-encoding, short or syntactically invalid keys, or data.go.kr rejections fail clearly instead of using fake sample data.

Flagship Tool

assess_lease_safety is the primary tool to show in a demo. It takes housingType, lawdCd, dealYmd, depositManwon, and optional situation details, then returns:

• an overall risk level with explicit reasons
• nearby rent-market median and sample transactions
• nearby sale-market median and deposit-to-sale ratio
• contract red flags from the user's situation
• immediate official next actions for registry, move-in report, fixed date, lease report, and HUG checks
• official source links used for the assessment

Production Configuration

Production requires DNS rebinding protection:

MCP_ALLOWED_HOSTS=your.playmcp.host,your.custom.domain

Use unique plain hostnames only. Do not include https://, ports, paths, whitespace, wildcards, blank comma-separated entries, underscores, empty labels, or labels that start or end with -.

Production also requires the official public-data key at startup because the flagship tool depends on live legal-dong, rent, and sale APIs:

DATA_GO_KR_SERVICE_KEY=your-data-go-kr-service-key

Optional bearer-token protection is available for direct deployments:

MCP_AUTH_TOKEN=replace-with-runtime-secret

When MCP_AUTH_TOKEN is set, it must be a real token, not a placeholder, at least 16 characters, free of whitespace, and visible ASCII only. POST /mcp then requires Authorization: Bearer <token>.

Optional request-size hardening is available for deployments with stricter ingress limits:

MCP_MAX_BODY_BYTES=262144

The default MCP request body limit is 262144 bytes, and the maximum accepted value is 1048576 bytes. Invalid values fail at startup instead of silently changing runtime behavior.

Optional MCP request rate limiting is available for public deployments:

MCP_RATE_LIMIT_PER_MINUTE=120

The default MCP POST rate limit is 120 requests per client per minute, and the maximum accepted value is 10000. Set MCP_RATE_LIMIT_PER_MINUTE=0 to disable it when an upstream gateway already enforces stricter limits.

Optional public-data timeout tuning is available when the deployment ingress has a tighter request budget:

PUBLIC_DATA_TIMEOUT_MS=8000

The default official public-data API timeout is 8000ms, with a maximum accepted value of 60000ms. Invalid values fail before requests are made.

Run Locally

Use Node.js 20 or newer with npm 10 or newer. .npmrc enables engine-strict=true, so unsupported runtimes fail during npm ci. It also sets ignore-scripts=true, so dependency lifecycle scripts do not run during install.

npm ci --ignore-scripts
npm run build
MCP_ALLOWED_HOSTS=127.0.0.1,localhost npm start

MCP endpoint:

http://127.0.0.1:3000/mcp

Smoke:

MCP_ENDPOINT=http://127.0.0.1:3000/mcp npm run smoke

Start a local server and run the MCP HTTP smoke in one command:

npm run smoke:http

Release preflight:

npm run preflight

npm run preflight runs working-tree, staged, and committed whitespace diff checks, secret scan, unit tests, PlayMCP validation, local MCP HTTP smoke with root route minimality, DNS-rebinding Host rejection, unsupported-method, invalid-JSON, unsupported-content-type, bearer-auth, and oversized-request rejection checks, MCP rate-limit smoke, production dependency audit, Docker build, Docker runtime smoke with the same MCP boundary checks, and live public-data smoke with extracted evidence-line validation when DATA_GO_KR_SERVICE_KEY is set.

Registration preflight:

DATA_GO_KR_SERVICE_KEY=... npm run preflight:registration

npm run preflight:registration runs the same checks but requires the live public-data smoke to run, pass for every supported housing type, and produce extractable registration evidence lines. Use it before PlayMCP registration.

For registration evidence in GitHub Actions, run the manual Registration Preflight workflow after adding DATA_GO_KR_SERVICE_KEY as a repository secret. Unlike the normal CI workflow, this workflow fails instead of skipping when the live public-data key is missing.

Live public-data smoke before production rollout:

DATA_GO_KR_SERVICE_KEY=... npm run smoke:public-data

By default, the live public-data smoke checks legal-dong lookup, rent-market APIs for all four housing types, sale-market APIs for all four housing types, and the flagship one-shot assessment for every selected housing type. Successful registration evidence includes legal_dong=ok, rent_market[...], sale_market[...], and lease_assessment[...] log lines for every selected housing type.

Optional overrides:

PUBLIC_DATA_SMOKE_REGION="서울 관악구" PUBLIC_DATA_SMOKE_LAWD_CD=11620 PUBLIC_DATA_SMOKE_DEAL_YMD=202605 DATA_GO_KR_SERVICE_KEY=... npm run smoke:public-data

To narrow the live smoke while debugging one source:

PUBLIC_DATA_SMOKE_HOUSING_TYPES=apartment,rowhouse DATA_GO_KR_SERVICE_KEY=... npm run smoke:public-data

Do not use a narrowed PUBLIC_DATA_SMOKE_HOUSING_TYPES list as registration evidence. npm run preflight:registration fails unless all supported housing types are included.

CI Gate

The repository includes .github/workflows/ci.yml for main. It runs:

• npm ci --ignore-scripts
• npm test
• npm run scan:secrets
• npm run validate:playmcp
• npm run smoke:http
• npm run smoke:rate-limit
• npm audit --omit=dev
• docker build -t lease-safe-mcp-ci .
• npm run smoke:docker

If the GitHub repository has a DATA_GO_KR_SERVICE_KEY secret, CI also runs the live public-data smoke against all supported housing types in registration mode and publishes the required housing coverage plus the extracted live public-data evidence lines in the job summary. Without that secret, the live API smoke is skipped and local pre-submission smoke should be run with the key.

Submission Checklist

Before registering in PlayMCP:

• Review SECURITY.md
• Review docs/submission.md
• Review docs/operations.md
• Run npm run preflight:registration locally with DATA_GO_KR_SERVICE_KEY set
• Run npm run check:github-secret and confirm the GitHub repository secret exists before trusting CI live-smoke evidence
• Run the manual GitHub Actions Registration Preflight workflow on the submitted commit
• Confirm the latest GitHub Actions CI run is green
• Confirm GitHub Actions live public-data smoke is passed, not skipped
• Configure the same DATA_GO_KR_SERVICE_KEY as a PlayMCP runtime environment variable
• Set MCP_ALLOWED_HOSTS to the PlayMCP host or deployment domain
• Use assess_lease_safety as the demo entry tool

PlayMCP in KC Git-source build:

• Git URL: https://github.com/hjongc/lease-safe-mcp.git
• Branch/ref: main
• Dockerfile path: Dockerfile
• PAT: empty if the repository is public