mcp

# 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. [](https://deepwiki.com/WordPress/mcp-adapter) ## Overview This adapter bridges WordPress's Abilities API with the [MCP specification](https://modelcontextprotocol.io/specification/2025-11-25/), 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 2025-11-25 specification](https://modelcontextprotocol.io/specification/2025-11-25/basic/transports) 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 ## Architecture For a full breakdown of the component structure, see the [Architecture Overview](docs/architecture/overview.md). ## Dependencies - **PHP**: >= 7.4 - **WordPress**: >= 6.9 - **[php-mcp-schema](https://github.com/WordPress/php-mcp-schema)** (`^0.1.0`): Typed DTOs for MCP protocol types — installed automatically via Composer ## Installation ### As a WordPress Plugin (Recommended) MCP Adapter is designed to be installed as a WordPress plugin. To install you should download the latest stable release from the [GitHub Releases page](https://github.com/WordPress/mcp-adapter/releases/latest) and install it like any other WordPress plugin. #### With WP-CLI ```bash wp plugin install https://github.com/WordPress/mcp-adapter/releases/latest/download/mcp-adapter.zip --activate ``` #### With WP-Env ```jsonc // .wp-env.json { "$schema": "https://schemas.wp.org/trunk/wp-env.json", "plugins": [ "https://github.com/WordPress/mcp-adapter/releases/latest/download/mcp-adapter.zip" ] } ``` ### As a Composer Library (for plugin developers) Plugin developers may wish to install MCP Adapter as a Composer dependency to integrate MCP functionality into their own plugins. ```bash composer require wordpress/mcp-adapter ``` #### Using Jetpack Autoloader (Highly Recommended) When multiple plugins use the MCP Adapter, it's highly recommended to use the [Jetpack Autoloader](https://github.com/Automattic/jetpack-autoloader) to prevent version conflicts. The Jetpack Autoloader ensures that only the latest version of shared packages is loaded, eliminating conflicts when different plugins use different versions of the same dependency. ```bash composer require automattic/jetpack-autoloader ``` Then load it in your main plugin file instead of the standard Composer autoloader: ```php <?php require_once plugin_dir_path( __FILE__ ) . 'vendor/autoload_packages.php'; ``` ### Using MCP Adapter in Your Plugin Check availability and initialize on `plugins_loaded` so all plugins are available before the adapter starts: ```php add_action( 'plugins_loaded', function() { if ( ! class_exists( 'WP\MCP\Core\McpAdapter' ) ) { // MCP Adapter is not active — show an admin notice or return early. return; } \WP\MCP\Core\McpAdapter::instance(); } ); ``` ## Basic Usage The MCP Adapter automatically creates a default server that exposes registered WordPress abilities through a layered architecture. This provides immediate MCP functionality without requiring manual server configuration. **How it works:** - WordPress abilities registered via `wp_register_ability()` with the `meta.mcp.public` flag set to `true` are discoverable and executable on the default server via its built-in adapter tools - On the default server, public abilities are accessed through `mcp-adapter/discover-abilities`, `mcp-adapter/get-ability-info`, and `mcp-adapter/execute-ability` rather than being auto-registered individually in `tools/list` - Alternatively, abilities can be explicitly listed when creating a [custom MCP server](#creating-custom-mcp-servers); in that case, they can be exposed directly as MCP tools, resources, or prompts without requiring the `meta.mcp.public` flag - The default server supports both HTTP and STDIO transports and supports multiple MCP protocol versions - Built-in error handling and observability are included - Access via HTTP: `/wp-json/mcp/mcp-adapter-default-server` - Access via STDIO: `wp mcp-adapter serve --server=mcp-adapter-default-server` <details> <summary><strong>Create a new ability (click to expand)</strong></summary> ```php // Simply register a WordPress ability add_action( 'wp_abilities_api_init', function() { wp_register_ability( 'my-plugin/get-posts', [ 'label' => 'Get Posts', 'description' => 'Retrieve WordPress posts with optional filtering', 'category' => 'site', 'input_schema' => [ 'type' => 'object', 'properties' => [ 'numberposts' => [ 'type' => 'integer', 'description' => 'Number of posts to retrieve', 'default' => 5, 'minimum' => 1, 'maximum' => 100 ], 'post_status' => [ 'type' => 'string', 'description' => 'Post status to filter by', 'enum' => ['publish', 'draft', 'private'], 'default' => 'publish' ] ] ], 'output_schema' => [ 'type' => 'array', 'items' => [ 'type' => 'object', 'properties' => [ 'ID' => ['type' => 'integer'], 'post_title' => ['type' => 'string'], 'post_content' => ['type' => 'string'], 'post_date' => ['type' => 'string'], 'post_author' => ['type' => 'string'] ] ] ], 'execute_callback' => function( $input ) { $args = [ 'numberposts' => $input['numberposts'] ?? 5, 'post_status' => $input['post_status'] ?? 'publish' ]; return get_posts( $args ); }, 'permission_callback' => function() { return current_user_can( 'read' ); }, 'meta' => [ 'mcp' => [ 'public' => true, // Required for default MCP server access ], ], ]); }); // With the meta.mcp.public flag, the ability is exposed through the default MCP server. // In the default server configuration, discover it via `discover-abilities` // and invoke it via `mcp-adapter/execute-ability` rather than expecting // it to appear as its own entry in `tools/list`. // Without the meta.mcp.public flag, abilities are only accessible // through custom MCP servers that explicitly list them. ``` </details> For detailed information about creating WordPress abilities, see the [Abilities API developer documentation](https://developer.wordpress.org/news/2025/11/introducing-the-wordpress-abilities-api/). ### Connecting to MCP Servers The MCP Adapter supports multiple connection methods. Here are examples for connecting with MCP clients: #### STDIO Transport (Local Development) For local development and testing, you can interact directly with MCP servers using WP-CLI commands: ```bash # List all available MCP servers wp mcp-adapter list # Test the discover abilities tool to see all available WordPress abilities echo '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"mcp-adapter-discover-abilities","arguments":{}}}' | wp mcp-adapter serve --user=admin --server=mcp-adapter-default-server # Test listing available tools echo '{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{}}' | wp mcp-adapter serve --user=admin --server=mcp-adapter-default-server ``` #### MCP Client Configuration Configure MCP clients (Claude Desktop, Claude Code, VS Code, Cursor, etc.) to connect to your WordPress MCP servers. <details> <summary><strong>STDIO Transport Configuration for local sites (click to expand)</strong></summary> ```json { "mcpServers": { "wordpress-default": { "command": "wp", "args": [ "--path=/path/to/your/wordpress/site", "mcp-adapter", "serve", "--server=mcp-adapter-default-server", "--user=admin" ] }, "wordpress-custom": { "command": "wp", "args": [ "--path=/path/to/your/wordpress/site", "mcp-adapter", "serve", "--server=your-custom-server-id", "--user=admin" ] } } } ``` </details> <details> <summary><strong>HTTP Transport via Proxy (click to expand)</strong></summary> The [`@automattic/mcp-wordpress-remote`](https://www.npmjs.com/package/@automattic/mcp-wordpress-remote) proxy runs locally and translates STDIO-based MCP communication from AI clients into HTTP REST API calls that WordPress understands. Authentication uses [WordPress Application Passwords](https://make.wordpress.org/core/2020/11/05/application-passwords-integration-guide/). ```json { "mcpServers": { "wordpress-http-default": { "command": "npx", "args": [ "-y", "@automattic/mcp-wordpress-remote@latest" ], "env": { "WP_API_URL": "http://your-site.test/wp-json/mcp/mcp-adapter-default-server", "LOG_FILE": "/path/to/logs/mcp-adapter.log", "WP_API_USERNAME": "your-username", "WP_API_PASSWORD": "your-application-password" } }, "wordpress-http-custom": { "command": "npx", "args": [ "-y", "@automattic/mcp-wordpress-remote@latest" ], "env": { "WP_API_URL": "http://your-site.test/wp-json/your-namespace/your-route", "LOG_FILE": "/path/to/logs/mcp-adapter.log", "WP_API_USERNAME": "your-username", "WP_API_PASSWORD": "your-application-password" } } } } ``` </details> ## Advanced Usage ### Creating Custom MCP Servers For advanced use cases, you can create custom MCP servers with specific configurations: ```php add_action( 'mcp_adapter_init', function( $adapter ) { $adapter->create_server( 'my-server-id', // Unique server identifier 'my-namespace', // REST API namespace 'mcp', // REST API route 'My MCP Server', // Server name 'Description of my server', // Server description 'v1.0.0', // Server version array( // Transport methods \WP\MCP\Transport\HttpTransport::class, ), \WP\MCP\Infrastructure\ErrorHandling\ErrorLogMcpErrorHandler::class, // Error handler \WP\MCP\Infrastructure\Observability\NullMcpObservabilityHandler::class, // Observability handler array( 'my-plugin/my-ability' ), // Abilities to expose as tools array(), // Resources (optional) array() // Prompts (optional) ); } ); ``` ### Custom Transport Implementation The MCP Adapter includes production-ready HTTP transports. For specialized requirements like custom authentication, message queues, or enterprise integrations, you can create custom transport protocols. See the [Custom Transports Guide](docs/guides/custom-transports.md) for detailed implementation instructions. ### Custom Transport Permissions The MCP Adapter supports custom authentication logic through transport permission callbacks. Instead of the default `is_user_logged_in()` check, you can implement custom authentication for your MCP servers. See the [Transport Permissions Guide](docs/guides/transport-permissions.md) for detailed authentication patterns. ### Custom Error Handler The MCP Adapter includes a default WordPress-compatible error handler, but you can implement custom error handling to integrate with existing logging systems, monitoring tools, or meet specific requirements. See the [Error Handling Guide](docs/guides/error-handling.md) for detailed implementation instructions. ### Custom Observability Handler The MCP Adapter includes built-in observability for tracking metrics and events. You can implement custom observability handlers to integrate with monitoring systems, analytics platforms, or performance tracking tools. See the [Observability Guide](docs/guides/observability.md) for detailed metrics tracking and custom handler implementation. ## Migration - [Migration Guide: v0.5.0](docs/migration/v0.5.0.md) — Breaking changes and upgrade instructions - [Migration Guide: v0.3.0](docs/migration/v0.3.0.md) — Transport, observability, and hook name changes ## License [GPL-2.0-or-later](https://spdx.org/licenses/GPL-2.0-or-later.html)