mcp-adapter

# MCP Adapter Part of the [**AI Building Blocks for WordPress** initiative](https://make.wordpress.org/ai/2025/07/17/ai-building-blocks) The official WordPress package for MCP integration that exposes WordPress abilities as [Model Context Protocol (MCP)](https://modelcontextprotocol.io) tools, resources, and prompts for AI agents. ## Overview This adapter bridges WordPress's Abilities API with the [MCP specification](https://modelcontextprotocol.io/specification/2025-06-18/), providing a standardized way for AI agents to interact with WordPress functionality. It includes HTTP and STDIO transport support, comprehensive error handling, and an extensible architecture for custom integrations. ## Features ### Core Functionality - **Ability-to-MCP Conversion**: Automatically converts WordPress abilities into MCP tools, resources, and prompts - **Multi-Server Management**: Create and manage multiple MCP servers with unique configurations - **Extensible Transport Layer**: - **HTTP Transport**: Unified transport implementing [MCP 2025-06-18 specification](https://modelcontextprotocol.io/specification/2025-06-18/basic/transports.md) for HTTP-based communication - **STDIO Transport**: Process-based communication via standard input/output for local development and CLI integration - **Custom Transport Support**: Implement `McpTransportInterface` to create specialized communication protocols - **Multi-Transport Configuration**: Configure servers with multiple transport methods simultaneously - **Flexible Error Handling**: - **Built-in Error Handler**: Default WordPress-compatible error logging included - **Custom Error Handlers**: Implement `McpErrorHandlerInterface` for custom logging, monitoring, or notification systems - **Server-specific Handlers**: Different error handling strategies per MCP server - **Observability**: - **Built-in Observability**: Default zero-overhead metrics tracking with configurable handlers - **Custom Observability Handlers**: Implement `McpObservabilityHandlerInterface` for integration with monitoring systems - **Validation**: Built-in validation for tools, resources, and prompts with extensible validation rules - **Permission Control**: Granular permission checking for all exposed functionality with configurable [transport permissions](docs/guides/transport-permissions.md) ### MCP Component Support - **[Tools](https://modelcontextprotocol.io/specification/2025-06-18/server/tools.md)**: Convert WordPress abilities into executable MCP tools for AI agent interactions - **[Resources](https://modelcontextprotocol.io/specification/2025-06-18/server/resources.md)**: Expose WordPress data as MCP resources for contextual information access - **[Prompts](https://modelcontextprotocol.io/specification/2025-06-18/server/prompts.md)**: Transform abilities into structured MCP prompts for AI guidance and templates - **Server Discovery**: Automatic registration and discovery of MCP servers following MCP protocol standards - **Built-in Abilities**: Core WordPress abilities for system introspection and ability management - **CLI Integration**: WP-CLI commands supporting STDIO transport as defined in MCP specification ## Understanding Abilities as MCP Components The MCP Adapter transforms WordPress abilities into MCP components: - **Tools**: WordPress abilities become executable MCP tools for AI agent interactions - **Resources**: WordPress abilities expose data as MCP resources for contextual information - **Prompts**: WordPress abilities provide structured MCP prompts for AI guidance For detailed information about MCP components, see the [Model Context Protocol specification](https://modelcontextprotocol.io/specification/2025-06-18/). ## Architecture ### Component Overview ``` ./includes/ │ # Core system components ├── Core/ │ ├── McpAdapter.php # Main registry and server management │ ├── McpServer.php # Individual server configuration │ ├── McpComponentRegistry.php # Component registration and management │ └── McpTransportFactory.php # Transport instantiation factory │ │ # Built-in abilities for MCP functionality ├── Abilities/ │ ├── DiscoverAbilitiesAbility.php # Ability discovery │ ├── ExecuteAbilityAbility.php # Ability execution │ └── GetAbilityInfoAbility.php # Ability introspection │ │ # CLI and STDIO transport support ├── Cli/ │ ├── McpCommand.php # WP-CLI commands │ └── StdioServerBridge.php # STDIO transport bridge │ │ # Business logic and MCP components ├── Domain/ │ │ # MCP Tools implementation │ ├── Tools/ │ │ ├── McpTool.php # Base tool class │ │ ├── RegisterAbilityAsMcpTool.php # Ability-to-tool conversion │ │ └── McpToolValidator.php # Tool validation │ │ # MCP Resources implementation │ ├── Resources/ │ │ ├── McpResource.php # Base resource class │ │ ├── RegisterAbilityAsMcpResource.php # Abili