Legal MCP Server

A Model Context Protocol (MCP) server that lets AI assistants and agents (Claude Desktop, Claude Code, IDE assistants or your own agent) search a legal document collection, read articles and cite them. Retrieval is handled by legal-hybrid-search (BM25 + dense + fusion), so the agent gets well-ranked results with ready-made citations instead of guessing.

Tools, resources and prompts

Design choices:

• Typed, validated inputs and outputs. Tools declare JSON Schemas (e.g. k between 1 and 20) and return structured results (Pydantic models), so clients get machine-readable output and bad arguments are rejected before any work runs.

• All tools are marked read-only (readOnlyHint, idempotentHint), so clients can allow them without asking for confirmation each time.

• Errors teach the agent how to recover. An unknown id returns "No article 'XX-9'. IDs look like 'RT-2' ...; act codes: CA, CR, DP, LC, RT" instead of a stack trace.

• Passages are merged per article, so long documents chunked for retrieval don't fill the results with duplicates.

• Logs go to stderr, because stdout carries the protocol over stdio.

• Two transports: stdio for desktop clients, and streamable HTTP (/mcp) for remote or multi-user deployments.

Related MCP server: mcp-fr-legal

Quick start

git clone https://github.com/samSignal/legal-mcp-server.git
cd legal-mcp-server
pip install -e ".[dev]"

python examples/client.py "my landlord will not return my deposit"   # scripted MCP client
npx @modelcontextprotocol/inspector legal-mcp                         # interactive MCP Inspector
legal-mcp --transport streamable-http --port 8000                     # HTTP endpoint at /mcp

Output of the example client (a real run):

Tools: search_legislation, get_article, list_acts, cite_article

Top results for: 'my landlord will not return my deposit'
  RT-2   Residential Tenancy Act (2017), Article 2 (Security deposit)
         The security **deposit** may **not** exceed two months' rent. The **landlord** shall **return** the **deposit** ...
  RT-7   Residential Tenancy Act (2017), Article 7 (Termination by the landlord)
  RT-4   Residential Tenancy Act (2017), Article 4 (Landlord's access to the premises)

Residential Tenancy Act (2017), Article 2 (Security deposit)
The security deposit may not exceed two months' rent. The landlord shall return the deposit within 30 days ...

Use it from Claude Desktop

Add this to claude_desktop_config.json (Settings → Developer → Edit Config), then restart Claude Desktop:

{
  "mcpServers": {
    "norland-legal": {
      "command": "legal-mcp"
    }
  }
}

If legal-mcp is not on your PATH, use the full path to your virtual environment's Python with "args": ["-m", "legal_mcp.server"]. Then ask, for example, "Using norland-legal, how much notice must my landlord give before visiting, and what's the citation?"

Use it from Claude Code

claude mcp add norland-legal -- legal-mcp

Tests

pytest -q runs 9 tests, and GitHub Actions runs them on Python 3.11 and 3.12 plus the example client on every push. Most tests use a real MCP client session rather than calling the functions directly:

• tool discovery, input/output schemas and read-only annotations

• the full search → get_article → cite workflow

• filters, schema validation (k=500 is rejected) and helpful error messages

• resources and prompts

• an end-to-end test that launches the server as a subprocess over stdio, the way Claude Desktop does

Project layout

legal_mcp/
  library.py   domain layer: search, article lookup, citations, snippets (no MCP code)
  server.py    MCP tools, resource and prompt; stdio / streamable-HTTP entry point
  data/        the document collection (fictional Norland statutes)
examples/client.py
tests/

Keeping the domain logic in library.py, separate from the protocol layer, means the same search and citation code could also sit behind a REST API or a LangGraph tool.

Note

The statutes are fictional, written for this project (see legal-hybrid-search). Nothing here is legal advice.

License

MIT.