PHP MCP Schema

A PHP representation of the Model Context Protocol (MCP) schema types.

This package provides Data Transfer Objects (DTOs), Enums, and Unions that mirror the official MCP TypeScript schema. It is not an SDK, client, or server implementation; just the type definitions for building your own MCP-compatible applications in PHP.

Installation

composer require wordpress/php-mcp-schema

Requires PHP 7.4 or higher.

Usage

Creating a Tool Definition

use WP\McpSchema\Server\Tools\DTO\Tool;

$tool = Tool::fromArray([
    'name' => 'get_weather',
    'description' => 'Get current weather for a location',
    'inputSchema' => [
        'type' => 'object',
        'properties' => [
            'location' => ['type' => 'string', 'description' => 'City name'],
        ],
        'required' => ['location'],
    ],
]);

Serialization (toArray)

Convert a DTO to a plain array for JSON encoding:

use WP\McpSchema\Server\Tools\DTO\Tool;

$tool = Tool::fromArray([
    'name' => 'get_weather',
    'description' => 'Get current weather for a location',
    'inputSchema' => ['type' => 'object', 'properties' => []],
]);

$array = $tool->toArray();
$json  = json_encode($array); // Ready to send over the wire

Deserialization (fromArray)

Decode incoming JSON into a fully typed DTO:

use WP\McpSchema\Server\Tools\DTO\CallToolRequest;

$json = '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"get_weather","arguments":{"location":"Paris"}}}';
$data = json_decode($json, true);

$request   = CallToolRequest::fromArray($data);
$tool_name = $request->getTypedParams()->getName(); // "get_weather"
$arguments = $request->getTypedParams()->getArguments(); // ['location' => 'Paris']

Factory / Union Types

Use a factory to resolve polymorphic content blocks without knowing the concrete type up front:

use WP\McpSchema\Common\Protocol\Factory\ContentBlockFactory;
use WP\McpSchema\Common\Content\DTO\TextContent;

$block = ContentBlockFactory::fromArray(['type' => 'text', 'text' => 'Hello, world!']);

// $block implements ContentBlockInterface; cast when you need the concrete API
if ($block instanceof TextContent) {
    echo $block->getText(); // "Hello, world!"
}

JSON-RPC Messages

Construct a generic JSON-RPC request for any MCP method:

use WP\McpSchema\Common\JsonRpc\DTO\JSONRPCRequest;

$request = JSONRPCRequest::fromArray([
    'jsonrpc' => '2.0',
    'id'      => 1,
    'method'  => 'tools/list',
]);

$json = json_encode($request->toArray());

Available Types

Server Types (WP\McpSchema\Server\)

• Tools - Tool, CallToolRequest, CallToolResult, ListToolsRequest, ListToolsResult
• Resources - Resource, ResourceTemplate, ReadResourceRequest, ReadResourceResult
• Prompts - Prompt, PromptMessage, GetPromptRequest, GetPromptResult
• Logging - LoggingMessageNotification, SetLevelRequest

Client Types (WP\McpSchema\Client\)

• Sampling - CreateMessageRequest, CreateMessageResult, SamplingMessage
• Elicitation - ElicitRequest, ElicitResult
• Roots - ListRootsRequest, ListRootsResult, Root

Common Types (WP\McpSchema\Common\)

• Protocol - InitializeRequest, InitializeResult, PingRequest
• Content - TextContent, ImageContent, AudioContent
• JSON-RPC - JSONRPCRequest, JSONRPCNotification, JSONRPCResultResponse, JSONRPCErrorResponse

Generator

The PHP code in src/ is auto-generated from the official MCP TypeScript schema. The generator is located in the generator/ directory and is not included in the Composer package.

See generator/README.md for setup and usage instructions.

License

GPL-2.0-or-later - see LICENSE.md for details.

Links

• Model Context Protocol Specification
• MCP GitHub Repository