Open Ontologies

What it does

Open Ontologies is a high-performance Rust-based MCP server designed for professional ontology engineering. It allows AI agents to build, validate, query, and reason over RDF/OWL ontologies using an in-memory Oxigraph triple store. It features a comprehensive pipeline for lifecycle management, including linting, versioning, and alignment, effectively acting as "Terraform for Knowledge Graphs."

Tools

It exposes 43 specialized tools including:

• onto_validate & onto_lint: Ensures ontology consistency and design quality.
• onto_reason: Native OWL2-DL SHOIQ tableaux reasoning for materializing inferred triples.
• onto_query: SPARQL 1.1 interface for complex data retrieval.
• onto_align: Cross-ontology class matching with confidence scoring.
• onto_marketplace: Direct installation of 32 standard W3C/ISO ontologies.
• onto_version: Snapshot-based version control and rollback.

Installation

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "open-ontologies": {
      "command": "/usr/local/bin/open-ontologies",
      "args": ["serve"]
    }
  }
}

Supported hosts

• claude
• cursor
• windsurf