MCP Core Library

This crate contains the domain business logic and ports of the MCP server following a hexagonal architecture.

Architectural Principles

Following the principles of hexagonal architecture, this crate:

• Contains only the domain business logic (pure logic) and ports (interfaces)
• Defines abstractions that represent domain boundaries
• Remains independent of implementation details and specific technologies

Main Components

• Primary/driving ports: Interfaces used by input adapters

  • Tool: Port defining the contract for tools executable via MCP

• Secondary/driven ports: Interfaces used by the domain to communicate with the outside world

  • Transport: Port defining the contract for network communication

• Domain entities and types: Fundamental domain data structures

  • Abstract message types (independent of specific formats like JSON-RPC)
  • Domain errors
  • Tool registry (ToolRegistry)

Note on Serialization

Specific protocol details like JSON-RPC are deliberately excluded from this domain crate and will be implemented in external adapters, in accordance with hexagonal architecture principles.

This crate only depends on basic crates like serde and tokio (for async types) to remain minimal and preserve domain isolation.

Roadmap

In addition to the main traits, the core crate defines other interfaces or structures for domain organization, such as ToolRegistry to manage the registration and search of tools by name. For immediate needs, a simple implementation internal to the core (with a HashMap<String, Box>) is sufficient, but could be formalized as a trait if different storage or loading strategies become necessary (e.g., for dynamic plugins).