⚖️ LexGuard MCP (법실마리)

An MCP server that connects Korean statutes, precedents, and statutory interpretations in a form that AI can easily understand

Based on official data from the National Law Information Center (Open Law), it provides statutes, articles, precedents, statutory interpretations, administrative appeals, and Constitutional Court decisions through a single question flow.

• How it runs: A self-hosted MCP server that you run with your own National Law Information Center API key (no separate hosting service)

• GitHub: https://github.com/SeoNaRu/lexguard-mcp

Quick Start (5 minutes)

1. Get an API key — Free issuance at open.law.go.kr. You must register your own IP when applying (see API Key Issuance below)

2. Run the server

   git clone https://github.com/SeoNaRu/lexguard-mcp
   cd lexguard-mcp
   cp .env.example .env        # LAW_API_KEY=발급키 설정
   docker compose up --build   # 또는: pip install -r requirements.txt && python -m src.main

3. Connect a client — MCP URL: http://localhost:9099/mcp

   • Cursor: Merge the contents of examples/cursor-mcp.local.json into .cursor/mcp.json

   • Claude Desktop: Merge examples/claude-desktop-mcp.local.json into the mcpServers section of claude_desktop_config.json (requires Node.js)

Static metadata for marketplaces and crawlers: mcp/manifest.json · Prompt index prompts/ · Resource URI guide resources/README.md · Cursor development skill .cursor/skills/lexguard-mcp-dev/SKILL.md

Why LexGuard?

The law often feels distant and difficult whenever you need it. High costs, unfamiliar terms, and a structure where you don't know where to start.

LexGuard MCP (LexGuard) started from this problem.

• Users ask questions in human language

• The AI analyzes the intent of the question

• Then provides clues based on official statute and precedent data

It does not replace judgment or legal advice. Rather, it aims to make the moment you first encounter the law less difficult.

Related MCP server: LexLink

Core Features

MCP Tools

legal_qa_tool — General-purpose legal QA

This is the single entry point for all legal questions. With one question, it searches statutes, precedents, interpretations, and committee decisions in parallel and synthesizes the results. For searches limited to a specific source (precedents only, interpretations only, etc.), you can consider the dedicated tools.

Capabilities

• Automatic classification across 10 domains

• Multi-intent detection and priority ordering

• Parallel search across statutes → precedents → interpretations → committees

• Natural language time condition filtering (automatic date_from / date_to conversion)

Input Schema

Example Prompts

프리랜서인데 근로자성 인정된 판례 있나요?
최근 3년 부당해고 판례 알려줘
개인정보 유출됐는데 법적으로 어떻게 되나요?
2023다12345 판례 찾아줘

law_article_tool — Precise statute article lookup

Directly looks up a specific provision when you know the statute name and article number. If legal_qa_tool is "search," this tool is "precise lookup."

Input Schema

Example Prompts

근로기준법 제50조 내용 알려줘
민법 제750조 3항이 뭐야?
개인정보보호법 제17조

law_comparison_tool — Old/new, history, and three-way comparison of statutes

Looks up old/new law comparison, legislative history, and three-way comparison results based on the statute name. Use law_article_tool for direct article text lookup and legal_qa_tool for general questions.

Input Schema

Example Prompts

XPP4

document_issue_tool — Contract and terms analysis

Paste a document to extract legal issues by clause and automatically search related statutes and precedents.

Input Schema

Supported Document Types

• labor — Employment contract / service contract

• lease — Lease agreement

• terms — Terms of use

Example Prompts

이 프리랜서 계약서 문제 있는지 봐줘
아래 임대차 계약서에서 불리한 조항 찾아줘

health — Server status check

Checks whether the MCP server is running, the API key configuration status, and environment variables.

Dedicated search tools (source-limited)

Use these when you want to find only specific data instead of the integrated search (legal_qa_tool).

Extended lookup tools

Use these when you need in-depth lookups such as supplementary statute information, history, forms, and links.

ministry_interpretation_tool — Per-ministry statutory interpretation

Searches the dedicated statutory interpretation (Q&A reply) database of 39 ministries. If interpretation_tool is an integrated search, this tool directly looks up only the interpretations of a specific ministry.

Supported ministries: Ministry of Employment and Labor, Ministry of Land, Infrastructure and Transport, Ministry of Economy and Finance, National Tax Service, Korea Customs Service, Ministry of Education, Ministry of Health and Welfare, Ministry of Justice, Ministry of Government Legislation, Ministry of Food and Drug Safety, National Police Agency, National Fire Agency, Korea Coast Guard, and 39 other agencies

law_history_tool — Statute and article change history

Tracks when and how a statute was amended.

Example Prompts

근로기준법 개정 이력 알려줘
개인정보보호법 제17조 조문 개정 내역

law_info_tool — Supplementary statute information

Looks up supplementary information such as English statutes, international treaties, statute structure diagrams, at-a-glance summaries, and abbreviations.

law_form_tool — Attached table/form search

Searches attached tables and forms of statutes, administrative rules, and local legislation by form name or related statute name.

law_link_tool — Statute-local legislation linkage lookup

Checks the list of ordinances linked to a specific statute, and the linkage status by competent ministry and local government.

MCP Prompts

Supports the prompts/list and prompts/get endpoints.

MCP Resources

Supports the resources/list and resources/read endpoints.

URI Scheme

Featured Resources (provided by default)

Major statutes such as the Labor Standards Act, Civil Act, Criminal Act, Personal Information Protection Act, Commercial Act, State Public Officials Act, and Administrative Litigation Act can be looked up immediately.

Installation

Method 1. Local (Python)

git clone https://github.com/SeoNaRu/lexguard-mcp
cd lexguard-mcp
pip install -r requirements.txt
cp .env.example .env   # LAW_API_KEY 설정
python -m src.main

Method 2. Docker Compose (recommended · close to one line)

git clone https://github.com/SeoNaRu/lexguard-mcp
cd lexguard-mcp
cp .env.example .env   # LAW_API_KEY 편집
docker compose up --build

Browser/client MCP URL: http://localhost:9099/mcp · Health: http://localhost:9099/health

Method 3. Docker (run only)

docker build -t lexguard-mcp .
docker run -p 9099:9099 -e LAW_API_KEY=your_key lexguard-mcp

Client connection

When the server is running locally, the MCP URL is http://localhost:9099/mcp.

Cursor (.cursor/mcp.json) — Same as the examples/cursor-mcp.local.json file:

{
  "mcpServers": {
    "lexguard-mcp": {
      "url": "http://localhost:9099/mcp"
    }
  }
}

Claude Desktop (claude_desktop_config.json) — Same as the examples/claude-desktop-mcp.local.json file. Claude Desktop does not directly support local HTTP URLs, so use the mcp-remote bridge (requires Node.js):

{
  "mcpServers": {
    "lexguard-mcp": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "http://localhost:9099/mcp"]
    }
  }
}

claude.ai web connector note: The web connector requires a public HTTPS URL, so it cannot connect to a locally running server. We recommend using Claude Desktop or Cursor. If you must use it on the web, deploy it on your own server (static IP + HTTPS) and register that IP with open.law.go.kr.

API Key issuance (required)

You need a National Law Information Center Open API key. Both issuance and usage are free.

1. Sign up at https://open.law.go.kr

2. Apply for OPEN API usage — you must register the IP or domain of the server (your PC) that will send requests. law.go.kr only allows requests from registered IPs.

3. Set LAW_API_KEY=your-issued-key in .env

Dynamic IP caution: Regular home connections may have changing IPs. If you get a "사용자 정보 검증에 실패하였습니다" error, re-register your current IP at [open.law.go.kr → API인증키관리].

DRF scheme selection

lexguard-mcp keeps the host/path of the National Law Information Center DRF URL fixed, and only the scheme can be selected via .env.

LAW_GO_KR_DRF_SCHEME=https

• Allowed values: http, https

• Default: https

• In restricted corporate networks/firewall environments, you may need the http://www.law.go.kr/DRF/... path as shown in the official guide examples.

This setting is an option to adjust the latent URL-generation problem, where hardcoded https could be accidentally hidden in normal environments, per operating environment.

Architecture

Client (Cursor / Claude)
    │ JSON-RPC 2.0 over SSE
    ▼
FastAPI  (/mcp POST)
    │ Rate Limiting (slowapi, 600 req/min/IP 기본값)
    ▼
MCP Routes  (tools/call · prompts/get · resources/read)
    │
    ▼
Services  (SmartSearchService · SituationGuidanceService)
    │ asyncio.gather (병렬 멀티 API 호출)
    ▼
Repositories  (Law · Precedent · Interpretation · Appeal · Constitutional …)
    │ httpx (동기/비동기 HTTP 클라이언트)
    │ TTLCache (검색 결과 30분 / 실패 5분)
    │ Exponential Backoff Retry
    ▼
국가법령정보센터 DRF API  (159개 엔트리 / 88개 unique target)

Search pipeline

질문 입력
    → 판례 번호 패턴 조기 감지 (2023다12345 / 2021헌마123)
    → 도메인 분류 + 의도(Intent) 분석
    → 시간 조건 파싱
    → asyncio.gather 병렬 API 호출
    → Reranker (BM25 + Keyword Hybrid 재정렬)
    → 응답 포매팅

Main technology stack

⚖️ LexGuard MCP (법실마리)

An MCP server that connects Korean statutes, precedents, and statutory interpretations in a form that AI can easily understand

Based on official data from the National Law Information Center (Open Law), it provides statutes, articles, precedents, statutory interpretations, administrative appeals, and Constitutional Court decisions through a single question flow.

• How it runs: A self-hosted MCP server that you run with your own National Law Information Center API key (no separate hosting service)

• GitHub: https://github.com/SeoNaRu/lexguard-mcp

Quick Start (5 minutes)

1. Get an API key — Free issuance at open.law.go.kr. You must register your own IP when applying (see API Key Issuance below)

2. Run the server

   git clone https://github.com/SeoNaRu/lexguard-mcp
   cd lexguard-mcp
   cp .env.example .env        # LAW_API_KEY=발급키 설정
   docker compose up --build   # 또는: pip install -r requirements.txt && python -m src.main

3. Connect a client — MCP URL: http://localhost:9099/mcp

   • Cursor: Merge the contents of examples/cursor-mcp.local.json into .cursor/mcp.json

   • Claude Desktop: Merge examples/claude-desktop-mcp.local.json into the mcpServers section of claude_desktop_config.json (requires Node.js)

Static metadata for marketplaces and crawlers: mcp/manifest.json · Prompt index prompts/ · Resource URI guide resources/README.md · Cursor development skill .cursor/skills/lexguard-mcp-dev/SKILL.md

Why LexGuard?

The law often feels distant and difficult whenever you need it. High costs, unfamiliar terms, and a structure where you don't know where to start.

LexGuard MCP (법실제) started from this problem.

• Users ask questions in human language

• The AI analyzes the intent of the question

• Then provides clues based on official statute and precedent data

It does not replace judgment or legal advice. Rather, it aims to make the moment you first encounter the law less difficult.

Core Features

MCP Tools

legal_qa_tool — General-purpose legal QA

This is the single entry point for all legal questions. With one question, it searches statutes, precedents, interpretations, and committee decisions in parallel and synthesizes the results. For searches limited to a specific source (precedents only, interpretations only, etc.), you can review the dedicated tools.

Capabilities

• Automatic classification across 10 domains

• Multi-intent detection and priority sorting

• Parallel search across statutes → precedents → interpretations → committee decisions

• Natural language time condition filtering (automatic date_from / date_to conversion)

Input Schema

Example Prompts

프리랜서인데 근로자성 인정된 판례 있나요?
최근 3년 부당해고 판례 알려줘
개인정보 유출됐는데 법적으로 어떻게 되나요?
2023다12345 판례 찾아줘

law_article_tool — Precise statute article lookup

Directly looks up a specific provision when you know the statute name and article number. If legal_qa_tool is "search," this tool is "precise lookup."

Input Schema

Example Prompts

근로기준법 제50조 내용 알려줘
민법 제750조 3항이 뭐야?
개인정보보호법 제17조

law_comparison_tool — Old/new, history, and three-way comparison of statutes

Provides old/new comparison, legislative history, and three-way comparison results based on the statute name. Use law_article_tool for direct article text lookup and legal_qa_tool for general questions.

Input Schema

Example Prompts

근로기준법 신구법 비교 보여줘
민법 연혁 조회

document_issue_tool — Contract and terms analysis

Paste a document to extract legal issues by clause and automatically search related statutes and precedents.

Input Schema

Supported Document Types

• labor — Employment contract / service contract

• lease — Lease agreement

• terms — Terms of use

Example Prompts

이 프리랜서 계약서 문제 있는지 봐줘
아래 임대차 계약서에서 불리한 조항 찾아줘

health — Server status check

Checks whether the MCP server is running, the API key configuration status, and environment variables.

Dedicated search tools (source-limited)

Use these when you want to find only specific data instead of the integrated search (legal_qa_tool).

Extended lookup tools

Use these when you need in-depth lookups such as supplementary statute information, history, forms, and links.

ministry_interpretation_tool — Per-ministry statutory interpretation

Searches the dedicated statutory interpretation (Q&A reply) database of 39 ministries. If interpretation_tool is an integrated search, this tool directly looks up only the interpretations of a specific ministry.

Supported ministries: Ministry of Employment and Labor, Ministry of Land, Infrastructure and Transport, Ministry of Economy and Finance, National Tax Service, Korea Customs Service, Ministry of Education, Ministry of Health and Welfare, Ministry of Justice, Ministry of Government Legislation, Ministry of Food and Drug Safety, National Police Agency, National Fire Agency, Korea Coast Guard, and 39 other agencies

law_history_tool — Statute and article change history

Tracks when and how a statute was amended.

Example Prompts

근로기준법 개정 이력 알려줘
개인정보보호법 제17조 조문 개정 내역

law_info_tool — Supplementary statute information

Provides supplementary information such as English statutes, international treaties, statute structure diagrams, at-a-glance views, and abbreviations.

law_form_tool — Attached table and form search

Searches attached tables and forms of statutes, administrative rules, and local legislation by form name or related statute name.

law_link_tool — Statute-local legislation linkage lookup

Checks the list of ordinances linked to a specific statute, and the linkage status by competent ministry and local government.

MCP Prompts

Supports the prompts/list and prompts/get endpoints.

MCP Resources

Supports the resources/list and resources/read endpoints.

URI Scheme

Featured Resources (provided by default)

Major statutes such as the Labor Standards Act, Civil Act, Criminal Act, Personal Information Protection Act, Commercial Act, State Public Officials Act, and Administrative Litigation Act can be looked up immediately.

Installation

Method 1. Local (Python)

git clone https://github.com/SeoNaRu/lexguard-mcp
cd lexguard-mcp
pip install -r requirements.txt
cp .env.example .env   # LAW_API_KEY 설정
python -m src.main

Method 2. Docker Compose (recommended · close to one line)

git clone https://github.com/SeoNaRu/lexguard-mcp
cd lexguard-mcp
cp .env.example .env   # LAW_API_KEY 편집
docker compose up --build

Browser/client MCP URL: http://localhost:9099/mcp · Health: http://localhost:9099/health

Method 3. Docker (run only)

docker build -t lexguard-mcp .
docker run -p 9099:9099 -e LAW_API_KEY=your_key lexguard-mcp

Client connection

When the server is running locally, the MCP URL is http://localhost:9099/mcp.

Cursor (.cursor/mcp.json) — Same as the examples/cursor-mcp.local.json file:

{
  "mcpServers": {
    "lexguard-mcp": {
      "url": "http://localhost:9099/mcp"
    }
  }
}

Claude Desktop (claude_desktop_config.json) — Same as the examples/claude-desktop-mcp.local.json file. Claude Desktop does not directly support local HTTP URLs, so use the mcp-remote bridge (requires Node.js):

{
  "mcpServers": {
    "lexguard-mcp": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "http://localhost:9099/mcp"]
    }
  }
}

claude.ai web connector guide: The web connector requires a public HTTPS URL, so it cannot connect to a locally running server. We recommend using Claude Desktop or Cursor. If you must use it on the web, deploy it on your own server (static IP + HTTPS) and register that IP with open.law.go.kr.

API Key Issuance (required)

A National Law Information Center Open API key is required. Both issuance and usage are free.

1. Sign up at https://open.law.go.kr

2. Apply for OPEN API usage — you must register the IP or domain of the server (your PC) that will send requests. law.go.kr only allows requests from registered IPs.

3. Set LAW_API_KEY=your-issued-key in .env

Dynamic IP caution: Regular home internet connections may have changing IPs. If you get a "사용자 정보 검증에 실패하였습니다" error, re-register your current IP at [open.law.go.kr → API인증키관리].

DRF scheme selection

lexguard-mcp keeps the host/path of the National Law Information Center DRF URL fixed, and only the scheme can be selected via .env.

LAW_GO_KR_DRF_SCHEME=https

• Allowed values: http, https

• Default: https

• In restricted corporate networks/firewall environments, you may need the http://www.law.go.kr/DRF/... path as shown in the official guide examples.

This setting is an option to adjust the latent URL-generation issue where hardcoded https could be accidentally hidden in normal environments, per operating environment.

Architecture

Client (Cursor / Claude)
    │ JSON-RPC 2.0 over SSE
    ▼
FastAPI  (/mcp POST)
    │ Rate Limiting (slowapi, 600 req/min/IP 기본값)
    ▼
MCP Routes  (tools/call · prompts/get · resources/read)
    │
    ▼
Services  (SmartSearchService · SituationGuidanceService)
    │ asyncio.gather (병렬 멀티 API 호출)
    ▼
Repositories  (Law · Precedent · Interpretation · Appeal · Constitutional …)
    │ httpx (동기/비동기 HTTP 클라이언트)
    │ TTLCache (검색 결과 30분 / 실패 5분)
    │ Exponential Backoff Retry
    ▼
국가법령정보센터 DRF API  (159개 엔트리 / 88개 unique target)

Search pipeline

질문 입력
    → 판례 번호 패턴 조기 감지 (2023다12345 / 2021헌마123)
    → 도메인 분류 + 의도(Intent) 분석
    → 시간 조건 파싱
    → asyncio.gather 병렬 API 호출
    → Reranker (BM25 + Keyword Hybrid 재정렬)
    → 응답 포매팅

Main technology stack

Development

# 테스트 실행
pytest tests/ -v

# 린트
ruff check src/

# 로컬 서버 (자동 재로드)
RELOAD=true python -m src.main

License

The full text is provided in the LICENSE file in the repository root.

• Usage: Same as MIT — research, personal, and commercial use, including modification, distribution, and resale, are permitted.

• When selling or offering for a fee: If you sell this software on its own or include it in a product or service, you must include the copyright notice and this license text in materials delivered to end users (documentation, credits/license screens, package metadata, etc.).

This notice is a summary; the original LICENSE text takes precedence.

Contribution

Issues & PRs are always welcome. Legal domain data, search quality improvements, and new MCP tool ideas are all welcome.

LexGuard MCP — We help you find the thread of legal information. The law is difficult, but the first thread can be easy.