php-types-validation

PHP MCP Types and Validation Guide

Core Type Definitions

PHP MCP SDK should use strong typing with PHP 8+ features to match TypeScript's type safety.

Protocol Version Constants

namespace MCP\Types;

final class Protocol {
    public const LATEST_PROTOCOL_VERSION = '2025-06-18';
    public const DEFAULT_NEGOTIATED_PROTOCOL_VERSION = '2025-03-26';
    public const SUPPORTED_PROTOCOL_VERSIONS = [
        '2025-06-18',
        '2025-03-26',
        '2024-11-05',
        '2024-10-07',
    ];
    public const JSONRPC_VERSION = '2.0';
}

Error Codes Enum

namespace MCP\Types;

enum ErrorCode: int {
    // SDK error codes
    case ConnectionClosed = -32000;
    case RequestTimeout = -32001;

    // Standard JSON-RPC error codes
    case ParseError = -32700;
    case InvalidRequest = -32600;
    case MethodNotFound = -32601;
    case InvalidParams = -32602;
    case InternalError = -32603;
}

Base Types

namespace MCP\Types;

/**
 * Base metadata interface
 */
interface BaseMetadata {
    public function getName(): string;
    public function getTitle(): ?string;
}

/**
 * Implementation info
 */
class Implementation implements BaseMetadata {
    public function __construct(
        private string $name,
        private string $version,
        private ?string $title = null
    ) {}

    public function getName(): string {
        return $this->name;
    }

    public function getVersion(): string {
        return $this->version;
    }

    public function getTitle(): ?string {
        return $this->title;
    }

    public function toArray(): array {
        $data = [
            'name' => $this->name,
            'version' => $this->version,
        ];

        if ($this->title !== null) {
            $data['title'] = $this->title;
        }

        return $data;
    }
}

Content Types

namespace MCP\Types\Content;

interface ContentBlock {
    public function getType(): string;
    public function toArray(): array;
}

class TextContent implements ContentBlock {
    public function __construct(
        private string $text,
        private array $meta = []
    ) {}

    public function getType(): string {
        return 'text';
    }

    public function getText(): string {
        return $this->text;
    }

    public function toArray(): array {
        $data = [
            'type' => 'text',
            'text' => $this->text,
        ];

        if (!empty($this->meta)) {
            $data['_meta'] = $this->meta;
        }

        return $data;
    }
}

class ImageContent implements ContentBlock {
    public function __construct(
        private string $data,
        private string $mimeType,
        private array $meta = []
    ) {}

    public function getType(): string {
        return 'image';
    }

    public function toArray(): array {
        return [
            'type' => 'image',
            'data' => $this->data,
            'mimeType' => $this->mimeType,
            '_meta' => $this->meta ?: null,
        ];
    }
}

class ResourceLink implements ContentBlock {
    public function __construct(
        private string $uri,
        private string $name,
        private ?string $title = null,
        private ?string $description = null,
        private ?string $mimeType = null
    ) {}

    public function getType(): string {
        return 'resource_link';
    }

    public function toArray(): array {
        return array_filter([
            'type' => 'resource_link',
            'uri' => $this->uri,
            'name' => $this->name,
            'title' => $this->title,
            'description' => $this->description,
            'mimeType' => $this->mimeType,
        ], fn($v) => $v !== null);
    }
}