MCP Server Expert

MCP Server Expert (onto2ai_mcp)

You are an expert on the neo4j_onto2ai_toolset/​onto2ai_mcp.py server. Use this skill to add new tools, troubleshoot connections, or change the server's execution mode.

Developer Guide

Adding New Tools

Register new tools using the @mcp.tool() decorator.

• Rules: Every tool must be async and have clear docstrings with argument descriptions.
• Type Hints: Use Union, List, Optional, and Dict from typing for robust tool signatures.
• Example:

@mcp.tool()
async def my_new_tool(param: str) -> str:
    """Description for my new tool."""
    return f"Processed {param}"

Execution Modes

The server supports two primary transports:

• Stdio (Default): Best for direct integration with local agents. Run with onto2ai-mcp or python -m neo4j_onto2ai_toolset.onto2ai_mcp.
• HTTP (SSE): Best for remote or shared access. Run with onto2ai-mcp http [port] or python -m neo4j_onto2ai_toolset.onto2ai_mcp http [port].

Key Dependencies

• FastMCP: The core framework for tool registration.
• Tool Config: Resolves database connections and LLM settings via neo4j_onto2ai_toolset/​onto2ai_tool_config.py.
• Logger: All events should be logged via the standard project logger.

Specialized Schema Tools

generate_schema_code (target_type='pydantic')

• Deterministically emits Python Enum classes when owl__NamedIndividual members are linked via rdf__type.
• Inheritance-aware: rdfs__subClassOf relationships in the DataModel drive proper Python class inheritance.
  • Child classes extend their parent Pydantic class (e.g., class TaxPayer(Person):) instead of BaseModel.
  • Inherited fields are omitted from child class bodies to avoid redefinition.
  • Classes are topologically sorted so parents always appear before children in the generated file.
• Key internal functions: _generate_pydantic_strict, _topo_sort, _inherited_aliases.

generate_neo4j_schema_description

Generates a structured Markdown summary with five sections:

1. Node Labels — subclass nodes shown with multi-label notation (e.g., TaxPayer:Person, Form1040_2025:IndividualTaxReturn).
2. Relationship Types — rdfs__subClassOf is excluded (inheritance is encoded via multi-label instead).
3. Node Properties — deduplicated by (label, property, type, mandatory); subclass label column uses multi-label.
4. Graph Topology — node patterns use multi-label notation; rdfs__subClassOf edges are omitted.
5. Enumeration Members — explicit table of owl__NamedIndividual members grouped by class.

Other Tools

• generate_schema_code (target_type='graph_schema'): Invokes the schema description logic for a deployment-ready representation.
• generate_neo4j_schema_constraint: Emits datatype IS NOT NULL constraints and enum-aware mandatory relationship comments.

Maintenance & Debugging

• JSON Outputs: When returning complex data, prefer returning Pydantic models (like DataModel) or well-structured dictionaries.
• Error Handling: Wrap tool logic in try/​except blocks and log errors before returning error messages to the client.
• CamelCase Utility: Use the internal to_camel_case() helper for normalizing Neo4j relationship types and property names.
• Server Restart Required: After editing onto2ai_mcp.py, the MCP server process must be restarted for changes to take effect.