Model Context Protocol client implementation for PHP

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.

This package is Treeware. If you use it in production, then we ask that you buy the world a tree to thank us for our work. By contributing to the Treeware forest you’ll be creating employment for local families and restoring wildlife habitats.