Installation

This document covers installation methods for the MCP Adapter, including Composer package installation, WordPress plugin installation, and dependency management. For setting up the development environment with wp-env and testing infrastructure, see Development Environment.

Installation Methods

The MCP Adapter can be installed in two ways: as a Composer package (recommended) or as a traditional WordPress plugin. Both methods require the WordPress Abilities API as a dependency.

Installation Method Comparison

Method	Use Case	Dependency Management	Activation
Composer Package	Plugin/theme integration	Jetpack Autoloader recommended	Automatic via McpAdapter::instance()
WordPress Plugin	Standalone installation	Composer install required	WordPress admin or WP-CLI

Composer Package Installation (Recommended)

The primary installation method uses Composer to install the MCP Adapter as a library dependency:

This method is defined in composer.json1-7 which specifies the package name as wordpress/mcp-adapter with type library and requires PHP 7.4 or higher composer.json73

Autoloading Configuration

The package uses PSR-4 autoloading with the namespace WP\MCP\ mapped to the includes/ directory composer.json60-64:

WP\MCP\ => includes/

For basic usage, load the Composer autoloader in your plugin:

Sources: docs/getting-started/installation.md1-35 composer.json60-74

WordPress Plugin Installation

Alternatively, install as a standalone WordPress plugin:

Installation Steps:

1. Clone the repository to wp-content/plugins/:

2. Install Composer dependencies:

3. Activate the plugin:

The plugin file at mcp-adapter.php20 handles initialization automatically when activated as a WordPress plugin.

Sources: docs/getting-started/installation.md143-167

Dependency Management with Jetpack Autoloader

Multi-Plugin Conflict Resolution

When multiple plugins use the MCP Adapter, version conflicts can occur. The Jetpack Autoloader resolves this by loading the latest compatible version of shared dependencies.

Installation:

The Jetpack Autoloader is configured as an allowed plugin in composer.json36-41:

Usage in Plugin:

Replace the standard Composer autoloader with Jetpack's autoloader:

This ensures that only the latest compatible version of each package is loaded, preventing fatal errors from duplicate class declarations.

Sources: docs/getting-started/installation.md15-40 composer.json36-41

Using MCP Adapter in Your Plugin

Plugin Integration Pattern

Dependency Checks:

docs/getting-started/installation.md66-76 demonstrates checking for required dependencies:

Hook Integration:

The plugin uses two WordPress hooks:

• wp_abilities_api_init - Register abilities docs/getting-started/installation.md84
• mcp_adapter_init - Create MCP server docs/getting-started/installation.md110

The complete example at docs/getting-started/installation.md47-141 shows the full integration pattern including ability registration and server creation.

Sources: docs/getting-started/installation.md42-141

Verifying Installation

Verification Methods

Method	Command/Location	Expected Result
WordPress Admin	Plugins → Installed Plugins	"MCP Adapter" listed as active
WP-CLI	wp plugin status mcp-adapter	Status: Active
REST API	curl https://yoursite.com/wp-json/	MCP routes listed
PHP Class Check	class_exists('WP\MCP\Core\McpAdapter')	Returns true

REST API Endpoint Test

Test the default MCP server endpoint docs/getting-started/installation.md180-189:

The default server endpoint is created automatically at /wp-json/mcp/mcp-adapter-default-server docs/getting-started/installation.md167

PHP Class Verification

Add this code temporarily to verify MCP Adapter is loaded docs/getting-started/installation.md195-203:

Sources: docs/getting-started/installation.md169-203

Troubleshooting

Common Installation Issues

Issue	Diagnosis	Solution
Plugin not found	Not in wp-content/plugins/mcp-adapter/	Clone repository or install via Composer
Plugin inactive	Not activated	Activate via WordPress admin or wp plugin activate mcp-adapter
Autoloader missing	vendor/autoload.php doesn't exist	Run composer install in plugin directory
Abilities API unavailable	wp_register_ability() not defined	Install and activate WordPress Abilities API
REST API not responding	Permalinks set to "Plain"	Change permalink structure in Settings → Permalinks

Debug Mode Configuration

Enable WordPress debug logging in wp-config.php docs/getting-started/installation.md231-235:

This enables logging to wp-content/debug.log for troubleshooting initialization issues.

Composer Autoloader Issues

If classes are not loading properly:

1. Verify vendor/autoload.php exists docs/getting-started/installation.md223-225
2. Check PSR-4 autoload configuration in composer.json60-64
3. Run composer dump-autoload to regenerate autoloader
4. Consider using Jetpack Autoloader for multi-plugin environments

Sources: docs/getting-started/installation.md205-237

Dependencies

Required Dependencies

Minimum Requirements:

Dependency	Version	Defined In
PHP	>= 7.4, <= 8.4	composer.json73 phpstan.neon.dist17-19
WordPress	>= 6.8	docs/getting-started/installation.md251
WordPress Abilities API	Latest	docs/getting-started/installation.md252

The composer.json30-31 file explicitly sets the platform PHP version to 7.4 to ensure compatibility:

PHPStan configuration at phpstan.neon.dist17-19 analyzes code compatibility across PHP 7.4 to 8.4:

Optional Dependencies

Dependency	Purpose	Usage
Jetpack Autoloader	Version conflict resolution	Multi-plugin environments
WP-CLI	Command-line testing	Development and STDIO transport

WP-CLI stubs are included as a development dependency composer.json77 and loaded in PHPStan configuration phpstan.neon.dist22

Sources: docs/getting-started/installation.md247-258 composer.json29-74 phpstan.neon.dist17-22

Automatic Initialization

When installed as a WordPress plugin, the MCP Adapter initializes automatically through mcp-adapter.php20 This creates a default MCP server accessible at:

/wp-json/mcp/mcp-adapter-default-server

The default server is configured with:

• Server ID: mcp-adapter-default-server
• HTTP transport enabled
• ErrorLog error handler
• All public abilities exposed (filtered by meta.mcp.public flag)

For custom server configuration and multi-server setups, see Server Configuration.

Sources: docs/getting-started/installation.md167-258