sample-mcp-server.php

<?php
// index.php - Simplified MCP Server entry point

// For demonstration, we'll use a simple routing mechanism.
// In a real application, you'd use a framework like Laravel, Symfony, etc.

$requestMethod = $_SERVER['REQUEST_METHOD'];
$requestUri = parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH);
$input = file_get_contents('php://input');
$data = json_decode($input, true); // Decode the incoming JSON payload

header('Content-Type: application/json');

// --- Simulate Basic Routing ---
if ($requestMethod === 'POST' && $requestUri === '/api/mcp/toolUse') {
    // This is where an AI client would send a tool call
    handleToolUse($data);
} elseif ($requestMethod === 'GET' && strpos($requestUri, '/api/mcp/resource/') === 0) {
    // This is where an AI client would request a resource
    handleResourceRequest($requestUri);
} else {
    http_response_code(404);
    echo json_encode(['error' => 'Not Found']);
}

// --- Function to handle tool calls ---
function handleToolUse($payload) {
    // In a real MCP server, you'd validate the payload structure based on the MCP spec.
    // For simplicity, we assume a basic 'toolName' and 'parameters'.

    $toolName = $payload['toolName'] ?? null;
    $parameters = $payload['parameters'] ?? [];

    if ($toolName === 'get_current_weather') {
        $city = $parameters['city'] ?? 'unknown';
        // Simulate calling an external weather API
        $weatherData = simulateWeatherApiCall($city);
        echo json_encode([
            'tool_result' => [
                'type' => 'tool_output', // As per MCP tool output message
                'tool_name' => $toolName,
                'content' => json_encode($weatherData) // Output usually as JSON string
            ]
        ]);
        http_response_code(200);
    } else {
        http_response_code(400);
        echo json_encode(['error' => 'Unknown tool', 'toolName' => $toolName]);
    }
}

// --- Function to handle resource requests ---
function handleResourceRequest($uri) {
    // Extract resource ID from URI, e.g., /api/mcp/resource/my_document_id
    $parts = explode('/', $uri);
    $resourceId = end($parts);

    if ($resourceId === 'my_document_id') {
        $documentContent = "This is the content of my important document.\nIt contains key information for the AI.";
        echo json_encode([
            'resource_content' => [
                'type' => 'resource_content', // As per MCP resource content message
                'resource_id' => $resourceId,
                'content_type' => 'text/plain',
                'content' => base64_encode($documentContent) // Base64 encode textual content
            ]
        ]);
        http_response_code(200);
    } else {
        http_response_code(404);
        echo json_encode(['error' => 'Resource not found', 'resourceId' => $resourceId]);
    }
}

// --- Simulate External API Calls ---
function simulateWeatherApiCall($city) {
    // In a real application, you'd use Guzzle or curl to call a real weather API (e.g., OpenWeatherMap)
    // For demonstration, we return mock data.
    $mockWeatherData = [
        'Cape Town' => ['temperature' => '18°C', 'conditions' => 'Partly cloudy', 'humidity' => '70%'],
        'London' => ['temperature' => '12°C', 'conditions' => 'Rainy', 'humidity' => '85%'],
        'New York' => ['temperature' => '25°C', 'conditions' => 'Sunny', 'humidity' => '60%'],
    ];
    return $mockWeatherData[$city] ?? ['temperature' => 'N/A', 'conditions' => 'unknown', 'humidity' => 'N/A'];
}

?>