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 setDiscovery() call needs symfony/finder:

composer require symfony/finder

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

Build a client