Calculator

MCP PHP SDK

The official PHP SDK for the Model Context Protocol (MCP). It provides a framework-agnostic API for implementing MCP servers and clients in PHP — tools, resources, prompts, STDIO and HTTP transports, sessions, authorization, and both protocol eras (the initialize handshake and the stateless 2026-07-28 revision).

This project represents a collaboration between the PHP Foundation and the Symfony project. It adopts development practices and standards from the Symfony project, including Coding Standards and the Backward Compatibility Promise.

Until the first major release, this SDK is considered experimental, please see the roadmap for planned next steps and features.

Protocol Conformance

Measured weekly against the MCP Conformance Test Framework, as passing checks out of total. The 2026-07-28 scores run against the framework's alpha releases, so they move as upstream publishes new scenarios.

Revision	Server	Client
2026-07-28
2025-11-25

Installation

composer require mcp/sdk

Build a server

A server is a plain PHP class plus three lines of wiring:

use Mcp\Capability\Attribute\McpResource;
use Mcp\Capability\Attribute\McpTool;
use Mcp\Server;
use Mcp\Server\Transport\StdioTransport;

class Calculator
{
    /**
     * Adds two numbers.
     */
    #[McpTool]
    public function add(int $a, int $b): int
    {
        return $a + $b;
    }

    #[McpResource(uri: 'config://calculator/settings')]
    public function settings(): array
    {
        return ['precision' => 2];
    }
}

exit(Server::builder()
    ->setServerInfo('Calculator', '1.0.0')
    ->setDiscovery(__DIR__, ['.'], excludeDirs: ['vendor'])
    ->build()
    ->run(new StdioTransport()));

The walkthrough in First server explains each piece, and Try it with the Inspector shows it running.

Build a client

use Mcp\Client;
use Mcp\Client\Transport\StdioTransport;

$client = Client::builder()
    ->setClientInfo('My Application', '1.0.0')
    ->build();

$client->connect(new StdioTransport(command: 'php', args: ['/path/to/server.php']));

$tools = $client->listTools();
$result = $client->callTool('add', ['a' => 5, 'b' => 3]);

$client->disconnect();

See Connecting to a server for transports, timeouts, and the handlers that answer server-initiated requests.

Documentation

The full documentation is published at php.sdk.modelcontextprotocol.io.

• Get started — Install the SDK and build your first server
• Servers — Tools, resources, resource templates, prompts, and how to register them
• Inside your handler — Talking back to the client, logging, and asking for input
• Running your server — Server builder, STDIO and HTTP transports, framework integration, sessions, authorization
• Clients — Client SDK for connecting to and communicating with MCP servers
• Protocol versions — The two protocol eras, and what revision 2026-07-28 changed
• Advanced — Events, protocol extensions (including MCP Apps), and custom message handlers
• Examples — Runnable server and client examples
• API Reference — Generated class reference

External Resources

• Model Context Protocol Documentation — Official MCP documentation
• Model Context Protocol Specification — Protocol specification
• Officially Supported Servers — Reference server implementations

PHP Libraries Using the MCP SDK

• api-platform/mcp — MCP integration for API Platform
• bnomei/kirby-mcp — MCP server for the Kirby CMS
• drupal/mcp_server — MCP server for Drupal exposing configuration and entities as MCP elements
• josbeir/cakephp-synapse — CakePHP plugin exposing application functionality over MCP
• nette/mcp-inspector — MCP server for introspecting Nette applications
• symfony/ai-mate — AI development assistant MCP server for Symfony projects
• symfony/mcp-bundle — Symfony integration bundle

Building something on top of the SDK? Open a pull request to add it to this list.

Contributing

We are passionate about supporting contributors of all levels of experience and would love to see you get involved in the project. Start by reporting issues or sending pull requests. See CONTRIBUTING.md for development setup, coding standards, and what to run before opening a PR.

Credits

The starting point for this SDK was the PHP-MCP project, initiated by Kyrian Obikwelu, and the Symfony AI initiative. We are grateful for the work done by both projects and their contributors, which created a solid foundation for this SDK.

License

This project is licensed under the Apache License, Version 2.0 for new contributions, with existing code under the MIT License — see the LICENSE file for details.