MEM Ontology MCP Server

An MCP (Model Context Protocol) server for querying the MEM (Metadata for Education Media) ontology, which models German school curricula across federal states (Bundesländer).

Features

The server provides the following tools:

1. sparql_query — Execute arbitrary SPARQL SELECT queries against the MEM triple store
2. list_bundeslaender — List all German federal states available in the ontology
3. list_schulfaecher — List all school subjects for a given state
4. list_schularten — List all school types for a given state
5. find_lehrplaene — Find curricula by state, optionally filtered by subject, school type, or grade level
6. get_lehrplan_tree — Get the hierarchical structure of a Lehrplan (bounded by depth, default 2, max 10)
7. get_children — Get direct children of a specific node (for drilling down into a branch)
8. search — Full-text search across all Lehrplan nodes by keyword (uses Virtuoso bif:contains), with optional Bundesland filter

Installation

npm install
npm run build

Configuration

Environment Variables

All configuration is via a .env file in the project root (loaded automatically at startup). Copy the example and edit as needed:

cp .env.example .env

The server will fail at startup if required variables are missing.

Infrastructure graphs (required):

Variable	Description
SPARQL_ENDPOINT	SPARQL endpoint URL
GRAPH_ONTOLOGY	Ontology graph URI
GRAPH_SCHULART	Schulart graph URI
GRAPH_SCHULFACH	Schulfach graph URI

State graphs (optional, add one per state):

Variable	Description
GRAPH_STATE_<CODE>	Graph URI for a state, e.g. GRAPH_STATE_SN, GRAPH_STATE_BY

State graphs are discovered dynamically — adding a new state requires only a new GRAPH_STATE_<CODE> entry in .env.

For Claude Code

Add a .mcp.json file in the project root:

{
  "mcpServers": {
    "mem-ontology": {
      "type": "stdio",
      "command": "node",
      "args": ["build/index.js"]
    }
  }
}

For Claude Desktop

Add to your MCP settings configuration file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "mem-ontology": {
      "command": "node",
      "args": ["/absolute/path/to/mem-ontologie-mcp/build/index.js"]
    }
  }
}

Usage Examples

Find biology curricula for Gymnasium in Sachsen

Tool: find_lehrplaene
Arguments: { "bundesland": "SN", "schulfach": "Biologie", "schulart": "Gymnasium" }

Browse the curriculum tree (depth-limited)

Tool: get_lehrplan_tree
Arguments: { "lehrplanUri": "https://lp-sachsen.org/resource/522", "depth": 2 }

Drill into a specific node

Tool: get_children
Arguments: { "nodeUri": "https://lp-sachsen.org/resource/7052" }

Search for a topic across all states

Tool: search
Arguments: { "query": "Wirbeltiere" }

Search within a specific state

Tool: search
Arguments: { "query": "Fische", "bundesland": "SN" }

State Codes

• BW — Baden-Württemberg
• BY — Bayern
• BE — Berlin
• BB — Brandenburg
• HB — Bremen
• HH — Hamburg
• HE — Hessen
• MV — Mecklenburg-Vorpommern
• NI — Niedersachsen
• NW — Nordrhein-Westfalen
• RP — Rheinland-Pfalz
• SL — Saarland
• SN — Sachsen
• ST — Sachsen-Anhalt
• SH — Schleswig-Holstein
• TH — Thüringen

Note: Currently, curriculum data is available for BY (Bayern), SN (Sachsen), and RP (Rheinland-Pfalz).

Architecture

• Transport: stdio (default) or Streamable HTTP (--http flag)
• SDK: @modelcontextprotocol/sdk with McpServer and zod schemas
• Data source: SPARQL endpoint (configurable via SPARQL_ENDPOINT env var)
• Runtime: Node.js, TypeScript, ES modules

Source files:

• src/index.ts — Main MCP server with all tool registrations
• src/http.ts — Streamable HTTP transport (Express server)
• src/sparql.ts — SPARQL query execution and result formatting

Development

npm run build      # Compile TypeScript
npm start          # Run the server (stdio)
npm run start:http # Run the server (HTTP)

HTTP Mode

Run with --http flag (or npm run start:http) to expose the MCP server as an HTTP service using Streamable HTTP transport.

Configuration (via .env or environment variables):

Variable	Default	Description
PORT	3000	HTTP listen port
API_KEY	(unset)	Bearer token for auth. If unset, auth is disabled.

Authentication: When API_KEY is set, all /mcp requests must include Authorization: Bearer <key>. Without API_KEY, the server is open access.

Client connection example:

# Test with MCP Inspector
npx @modelcontextprotocol/inspector --url http://localhost:3000/mcp

# With authentication
npx @modelcontextprotocol/inspector --url http://localhost:3000/mcp --header "Authorization: Bearer your-secret-key-here"

Deployment (Docker)

A Dockerfile and docker-compose.yml are included for self-hosted deployment. The container runs the server in HTTP mode behind your own reverse proxy (TLS is expected to be terminated upstream).

# Copy and edit your environment.
cp .env.example .env
# Set API_KEY to a random secret for production.

# Build and start.
docker compose up -d --build

# Logs
docker compose logs -f

By default the container binds to 127.0.0.1:3000 on the host, so it's only reachable via a reverse proxy on the same machine. Adjust the ports: entry in docker-compose.yml if you need LAN exposure.

Reverse proxy example (Caddy)

mcp.example.org {
    reverse_proxy 127.0.0.1:3000
}

Reverse proxy example (nginx)

location /mcp {
    proxy_pass http://127.0.0.1:3000/mcp;
    proxy_http_version 1.1;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
    # Streamable HTTP uses SSE for server->client messages.
    proxy_buffering off;
    proxy_read_timeout 3600s;
}

Clients then connect to https://mcp.example.org/mcp with Authorization: Bearer <API_KEY>.

License

Unlicense