Model Context Protocol client implementation for PHP

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A PHP client library for interacting with Model Context Protocol (MCP) servers.

Installation

You can install the package via composer:

composer require swisnl/mcp-client

Requirements

• PHP 8.2 or higher
• ReactPHP packages

Features

• Multiple transport mechanisms:
  • SSE (Server-Sent Events)
  • Stdio (Standard input/output)
  • Process (External process communication)
  • StreamableHttp (HTTP with session management)
• Promise-based API with ReactPHP
• PSR-3 Logger interface support
• Most of MCP protocol support (2025-03-26)
• Tool annotation support

Basic Usage

SSE Transport

use Swis\McpClient\Client;
// Create client with SSE transporter
$endpoint = 'https://your-mcp-server.com/sse';
$client = Client::withSse($endpoint);
// Connect to the server
$client->connect(function($initResponse) {
 echo "Connected to server: " . json_encode($initResponse['serverInfo']) . "\n";
});
// List available tools
$tools = $client->listTools();
foreach ($tools->getTools() as $tool) {
 echo "- {$tool->getName()}: {$tool->getDescription()}\n";
 // Access tool annotations if available
 if ($annotations = $tool->getAnnotations()) {
 echo " * Read-only: " . ($annotations->getReadOnlyHint() ? 'Yes' : 'No') . "\n";
 echo " * Title: " . ($annotations->getTitle() ?? 'N/A') . "\n";
 }
}
// Call a tool
$result = $client->callTool('echo', ['message' => 'Hello World!']);
echo $result->getResult() . "\n";

Process Transport

use Swis\McpClient\Client;
// Create client with a process transporter
[$client, $process] = Client::withProcess('/path/to/mcp-server/binary');
// Connect to the server
$client->connect();
// Use the client...
// Disconnect when done
$client->disconnect();

StreamableHttp Transport

use Swis\McpClient\Client;
// Create client with StreamableHttp transporter
$endpoint = 'https://your-mcp-server.com/';
$client = Client::withStreamableHttp($endpoint);
// Connect to the server
$client->connect();
// The transporter will automatically manage session IDs from the Mcp-Session-Id header
// Use the client...
// Disconnect when done
$client->disconnect();

Use in combination with Agents SDK

First, install Agents SDK

composer require swisnl/agents-sdk

use Swis\Agents\Agent;
use Swis\Agents\Mcp\McpConnection;
use Swis\McpClient\Client;
use Swis\Agents\Orchestrator;
$agent = new Agent(
 name: 'Calculator Agent',
 description: 'This Agent can perform arithmetic operations.',
 mcpConnections: [
 new MathMcpConnection(),
 ]
);
$orchestrator = new Orchestrator($agent);
echo $orchestrator
 ->withUserInstruction('What\'s 5 + 5?')
 ->run($agent)
class MathMcpConnection extends McpConnection
{
 public function __construct()
 {
 [$client, $process] = Client::withProcess(
 command: 'node ' . realpath(__DIR__ . '/node_modules/math-mcp/build/index.js'),
 );
 parent::__construct(
 client: $client,
 name: 'Math MCP',
 );
 }
}

Advanced Usage

Custom Transporter

You can implement your own transporter by implementing the TransporterInterface:

use Swis\McpClient\TransporterInterface;
use Swis\McpClient\EventDispatcher;
class CustomTransporter implements TransporterInterface
{
 // Implement required methods
}
// Create a client with your custom transporter
$transporter = new CustomTransporter();
$eventDispatcher = new EventDispatcher();
$client = new Client($transporter, $eventDispatcher);

Async Operations

The client supports async operations using ReactPHP promises:

$client->sendRequest(new ListToolsRequest())->then(...);

License

This package is open-sourced software licensed under the MIT license.

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