Sunbelt Computer Software

PHP MCP Server

Core PHP implementation of the Model Context Protocol (MCP) server.

Introduction

The Model Context Protocol (MCP) is an open standard, initially developed by Anthropic, designed to standardize how AI assistants and tools connect to external data sources, APIs, and other systems. Think of it like USB-C for AI – a single, consistent way to provide context.

php-mcp/server is a PHP library that makes it incredibly easy to build MCP-compliant servers. Its core goal is to allow you to expose parts of your existing PHP application – specific methods – as MCP Tools, Resources, or Prompts with minimal effort, primarily using PHP 8 Attributes.

This package currently supports the 2024-11-05 version of the Model Context Protocol and is compatible with various MCP clients like Claude Desktop, Cursor, Windsurf, and others that adhere to this protocol version.

Key Features

Attribute-Based Definition: Define MCP elements (Tools, Resources, Prompts, Templates) using simple PHP 8 Attributes (#[McpTool], #[McpResource], #[McpPrompt], #[McpResourceTemplate], #[McpTemplate]) on your methods or directly on invokable classes.
Manual Registration: Programmatically register MCP elements using fluent methods on the Server instance (e.g., ->withTool(), ->withResource()).
Automatic Metadata Inference: Leverages method names, parameter names, PHP type hints (for schema), and DocBlocks (for schema and descriptions) to automatically generate MCP definitions, minimizing boilerplate code.
PSR Compliant: Integrates seamlessly with standard PHP interfaces:
- PSR-3 (LoggerInterface): Bring your own logger (e.g., Monolog).
- PSR-11 (ContainerInterface): Use your favorite DI container (e.g., Laravel, Symfony, PHP-DI) for resolving your application classes and their dependencies when MCP elements are invoked.
- PSR-16 (SimpleCacheInterface): Provide a cache implementation (e.g., Symfony Cache, Laravel Cache) for discovered elements and transport state.
Flexible Configuration: Starts with sensible defaults but allows providing your own implementations for logging, caching, DI container, and detailed MCP configuration (ConfigurationRepositoryInterface).
Multiple Transports: Supports stdio (for command-line clients) and includes components for building http+sse (HTTP + Server-Sent Events) transports out-of-the-box (requires integration with a HTTP server).
Automatic Discovery: Scans specified directories within your project to find classes and methods annotated with MCP attributes.
Framework Agnostic: Designed to work equally well in vanilla PHP projects or integrated into any PHP framework.

Requirements

PHP >= 8.1
Composer

Installation

You can install the package via Composer:

composer require php-mcp/server

Note: For Laravel applications, consider using the dedicated php-mcp/laravel package. It builds upon this core library, providing helpful integrations, configuration options, and Artisan commands specifically tailored for the Laravel framework.

Getting Started: A Simple `stdio` Server

Here's a minimal example demonstrating how to expose a simple PHP class method as an MCP Tool using the stdio transport.

1. Create your MCP Element Class:

Create a file, for example, src/MyMcpStuff.php:

<?php

namespace App;

use PhpMcp\Server\Attributes\McpTool;

class MyMcpStuff
{
    /**
     * A simple tool to add two numbers.
     *
     * @param int $a The first number.
     * @param int $b The second number.
     * @return int The sum of the two numbers.
     */
    #[McpTool(name: 'adder')]
    public function addNumbers(int $a, int $b): int
    {
        return $a + $b;
    }
}

2. Create the Server Script:

Create a script, e.g., mcp-server.php, in your project root:

<?php

declare(strict_types=1);

use PhpMcp\Server\Server;

// Ensure your project's autoloader is included
require_once __DIR__ . '/vendor/autoload.php';
// If your MCP elements are in a specific namespace, ensure that's autoloaded too (e.g., via composer.json)

// Optional: Configure logging (defaults to STDERR)
// $logger = new MyPsrLoggerImplementation(...);

$server = Server::make()
    // Optional: ->withLogger($logger)
    // Optional: ->withCache(new MyPsrCacheImplementation(...))
    // Optional: ->withContainer(new MyPsrContainerImplementation(...))
    ->withBasePath(__DIR__) // Directory to start scanning for Attributes
    ->withScanDirectories(['src']) // Specific subdirectories to scan (relative to basePath)
    ->discover(); // Find all #[Mcp*] attributes

// Run the server using the stdio transport
$exitCode = $server->run('stdio');

exit($exitCode);

3. Configure your MCP Client:

Configure your MCP client (like Cursor, Claude Desktop, etc.) to connect using the stdio transport. This typically involves specifying the command to run the server script. For example, in Cursor's .cursor/mcp.json:

{
    "mcpServers": {
        "my-php-server": {
            "command": "php",
            "args": [
                "/path/to/your/project/mcp-server.php"
            ]
        }
    }
}

Replace /path/to/your/project/mcp-server.php with the actual absolute path to your script.

Now, when you connect your client, it should discover the adder tool.

Core Concepts

The primary ways to expose functionality through php-mcp/server are:

Attribute Discovery: Decorating your PHP methods or invokable classes with specific Attributes (#[McpTool], #[McpResource], etc.). The server automatically discovers these during the ->discover() process.
Manual Registration: Using fluent methods (->withTool(), ->withResource(), etc.) on the Server instance before running it.

Attributes for Discovery

These attributes mark classes or methods to be found by the ->discover() process.

`#[McpTool]`

Marks a method or an invokable class as an MCP Tool. Tools represent actions or functions the client can invoke, often with parameters.

Usage:

On a Method: Place the attribute directly above a public, non-static method.
On an Invokable Class: Place the attribute directly above a class definition that contains a public __invoke method. The __invoke method will be treated as the tool's handler.

The attribute accepts the following parameters:

name (optional): The name of the tool exposed to the client.
- When on a method, defaults to the method name (e.g., addNumbers becomes addNumbers).
- When on an invokable class, defaults to the class's short name (e.g., class AdderTool becomes AdderTool).
description (optional): A description for the tool. Defaults to the method's DocBlock summary (or the __invoke method's summary if on a class).

The parameters (including name, type hints, and defaults) of the target method (or __invoke) define the tool's input schema. The return type hint defines the output schema. DocBlock @param and @return descriptions are used for parameter/output descriptions.

Return Value Formatting

The value returned by your method determines the content sent back to the client. The library automatically formats common types:

null: Returns empty content (if return type hint is void) or TextContent with (null).
string, int, float, bool: Automatically wrapped in PhpMcp\Server\JsonRpc\Contents\TextContent.
array, object: Automatically JSON-encoded (pretty-printed) and wrapped in TextContent.
PhpMcp\Server\JsonRpc\Contents\Content object(s): If you return an instance of Content (e.g., TextContent, ImageContent, AudioContent, ResourceContent) or an array of Content objects, they are used directly. This gives you full control over the output format. Example: return TextContent::code('echo \'Hello\';', 'php');
Exceptions: If your method throws an exception, a TextContent containing the error message and type is returned.

The method's return type hint (@return tag in DocBlock) is used to generate the tool's output schema, but the actual formatting depends on the value returned at runtime.

/**
 * Fetches user details by ID.
 *
 * @param int $userId The ID of the user to fetch.
 * @param bool $includeEmail Include the email address?
 * @return array{id: int, name: string, email?: string} User details.
 */
#[McpTool(name: 'get_user')]
public function getUserById(int $userId, bool $includeEmail = false): array
{
    // ... implementation returning an array ...
}

/**
 * Returns PHP code as formatted text.
 *
 * @return TextContent
 */
#[McpTool(name: 'get_php_code')]
public function getPhpCode(): TextContent
{
    return TextContent::code('<?php echo \'Hello World\';', 'php');
}

/**
 * An invokable class acting as a tool.
 */
#[McpTool(description: 'An invokable adder tool.')]
class AdderTool {
    /**
     * Adds two numbers.
     * @param int $a First number.
     * @param int $b Second number.
     * @return int The sum.
     */
    public function __invoke(int $a, int $b): int {
        return $a + $b;
    }
}

`#[McpResource]`

Marks a method or an invokable class as representing a specific, static MCP Resource instance. Resources represent pieces of content or data identified by a URI. The target method (or __invoke) will typically be called when a client performs a resources/read for the specified URI.

Usage:

On a Method: Place the attribute directly above a public, non-static method.
On an Invokable Class: Place the attribute directly above a class definition that contains a public __invoke method. The __invoke method will be treated as the resource handler.

The attribute accepts the following parameters:

uri (required): The unique URI for this resource instance (e.g., config://app/settings, file:///data/status.txt). Must conform to RFC 3986.
name (optional): Human-readable name. Defaults inferred from method name or class short name.
description (optional): Description. Defaults to DocBlock summary of the method or __invoke.
mimeType (optional): The resource's MIME type (e.g., text/plain, application/json).
size (optional): Resource size in bytes, if known and static.
annotations (optional): Array of MCP annotations (e.g., ['audience' => ['user']]).

The target method (or __invoke) should return the content of the resource.

Return Value Formatting

The return value determines the resource content:

string: Treated as text content. MIME type is taken from the attribute or guessed (text/plain, application/json, text/html).
array: If the attribute's mimeType is application/json (or contains json), the array is JSON-encoded. Otherwise, it attempts JSON encoding with a warning.
stream resource: Content is read from the stream. mimeType must be provided in the attribute or defaults to application/octet-stream.
SplFileInfo object: Content is read from the file. mimeType is taken from the attribute or guessed.
PhpMcp\Server\JsonRpc\Contents\EmbeddedResource: Used directly. Gives full control over URI, MIME type, text/blob content.
PhpMcp\Server\JsonRpc\Contents\ResourceContent: The inner EmbeddedResource is extracted and used.
array{'blob': string, 'mimeType'?: string}: Creates a blob resource.
array{'text': string, 'mimeType'?: string}: Creates a text resource.

#[McpResource(uri: 'status://system/load', mimeType: 'text/plain')]
public function getSystemLoad(): string
{
    return file_get_contents('/proc/loadavg');
}

/**
 * An invokable class providing system load resource.
 */
#[McpResource(uri: 'status://system/load/invokable', mimeType: 'text/plain')]
class SystemLoadResource {
    public function __invoke(): string {
        return file_get_contents('/proc/loadavg');
    }
}

`#[McpResourceTemplate]`

Marks a method or an invokable class that can generate resource instances based on a template URI. This is useful for resources whose URI contains variable parts (like user IDs or document IDs). The target method (or __invoke) will be called when a client performs a resources/read matching the template.

Usage:

On a Method: Place the attribute directly above a public, non-static method.
On an Invokable Class: Place the attribute directly above a class definition that contains a public __invoke method.

The attribute accepts the following parameters:

uriTemplate (required): The URI template string, conforming to RFC 6570 (e.g., user://{userId}/profile, document://{docId}?format={fmt}).
name, description, mimeType, annotations (optional): Similar to #[McpResource], but describe the template itself. Defaults inferred from method/class name and DocBlocks.

The parameters of the target method (or __invoke) must match the variables defined in the uriTemplate. The method should return the content for the resolved resource instance.

Return Value Formatting

Same as #[McpResource] (see above). The returned value represents the content of the resolved resource instance.

/**
 * Gets a user's profile data.
 *
 * @param string $userId The user ID from the URI.
 * @return array The user profile.
 */
#[McpResourceTemplate(uriTemplate: 'user://{userId}/profile', name: 'user_profile', mimeType: 'application/json')]
public function getUserProfile(string $userId): array
{
    // Fetch user profile for $userId
    return ['id' => $userId, /* ... */ ];
}

/**
 * An invokable class providing user profiles via template.
 */
#[McpResourceTemplate(uriTemplate: 'user://{userId}/profile/invokable', name: 'user_profile_invokable', mimeType: 'application/json')]
class UserProfileTemplate {
    /**
     * Gets a user's profile data.
     * @param string $userId The user ID from the URI.
     * @return array The user profile.
     */
    public function __invoke(string $userId): array {
        // Fetch user profile for $userId
        return ['id' => $userId, 'source' => 'invokable', /* ... */ ];
    }
}

`#[McpPrompt]`

Marks a method or an invokable class as an MCP Prompt generator. Prompts are pre-defined templates or functions that generate conversational messages (like user or assistant turns) based on input parameters.

Usage:

On a Method: Place the attribute directly above a public, non-static method.
On an Invokable Class: Place the attribute directly above a class definition that contains a public __invoke method.

The attribute accepts the following parameters:

name (optional): The prompt name. Defaults to method name or class short name.
description (optional): Description. Defaults to DocBlock summary of the method or __invoke.

Method parameters (or __invoke parameters) define the prompt's input arguments. The method should return the prompt content, typically an array conforming to the MCP message structure.

Return Value Formatting

Your method should return the prompt messages in one of these formats:

Array of PhpMcp\Server\JsonRpc\Contents\PromptMessage objects: The recommended way for full control.
- PromptMessage::user(string|Content $content)
- PromptMessage::assistant(string|Content $content)
- The $content can be a simple string (becomes TextContent) or any Content object (TextContent, ImageContent, ResourceContent, etc.).
Simple list array: [['role' => 'user', 'content' => 'Some text'], ['role' => 'assistant', 'content' => $someContentObject]]
- role must be 'user' or 'assistant'.
- content can be a string (becomes TextContent) or a Content object.
- content can also be an array structure like ['type' => 'image', 'data' => '...', 'mimeType' => '...'], ['type' => 'text', 'text' => '...'], or ['type' => 'resource', 'resource' => ['uri' => '...', 'text|blob' => '...']].
Simple associative array: ['user' => 'User prompt text', 'assistant' => 'Optional assistant prefix'] (converted to one or two PromptMessages with TextContent).

/**
 * Generates a prompt to summarize text.
 *
 * @param string $textToSummarize The text to summarize.
 * @return array The prompt messages.
 */
#[McpPrompt(name: 'summarize')]
public function generateSummaryPrompt(string $textToSummarize): array
{
    return [
        ['role' => 'user', 'content' => "Summarize the following text:\n\n{$textToSummarize}"],
    ];
}

/**
 * An invokable class generating a summary prompt.
 */
#[McpPrompt(name: 'summarize_invokable')]
class SummarizePrompt {
     /**
     * Generates a prompt to summarize text.
     * @param string $textToSummarize The text to summarize.
     * @return array The prompt messages.
     */
    public function __invoke(string $textToSummarize): array {
        return [
            ['role' => 'user', 'content' => "[Invokable] Summarize:

{$textToSummarize}"],
        ];
    }
}

The `Server` Fluent Interface

The PhpMcp\Server\Server class is the main entry point for configuring and running your MCP server. It provides a fluent interface (method chaining) to set up dependencies, parameters, and manually register elements.

Server::make(): self: Static factory method to create a new server instance. It initializes the server with default implementations for core services (Logger, Cache, Config, Container).
->withLogger(LoggerInterface $logger): self: Provide a PSR-3 compliant logger implementation. By default, logging is disabled unless a logger is explicitly provided here (when using the default container) or registered in a custom container.
- If using the default BasicContainer: This method replaces the default no-op logger and updates the registration within the BasicContainer, enabling logging.
- If using a custom container: This method only sets an internal property on the Server instance. It does not affect the custom container. You should register your desired LoggerInterface directly within your container setup to enable logging.
->withCache(CacheInterface $cache): self: Provide a PSR-16 compliant cache implementation.
- If using the default BasicContainer: This method replaces the default FileCache instance and updates the registration within the BasicContainer.
- If using a custom container: This method only sets an internal property on the Server instance. It does not affect the custom container. You should register your desired CacheInterface directly within your container setup.
->withContainer(ContainerInterface $container): self: Provide a PSR-11 compliant DI container.
- When called, the server will use this container for all dependency resolution, including its internal needs and instantiating your handler classes.
- Crucially, you MUST ensure this container is configured to provide implementations for LoggerInterface, CacheInterface, and ConfigurationRepositoryInterface, as the server relies on these.
- If not called, the server uses its internal BasicContainer with built-in defaults.
->withConfig(ConfigurationRepositoryInterface $config): self: Provide a custom configuration repository.
- If using the default BasicContainer: This method replaces the default ArrayConfigurationRepository instance and updates the registration within the BasicContainer.
- If using a custom container: This method only sets an internal property on the Server instance. It does not affect the custom container. You should register your desired ConfigurationRepositoryInterface directly within your container setup.
->withBasePath(string $path): self: Set the absolute base path for directory scanning during discovery. Defaults to the parent directory of vendor/php-mcp/server.
->withScanDirectories(array $dirs): self: Specify an array of directory paths relative to the basePath where the server should look for annotated classes/methods during discovery. Defaults to ['.', 'src/MCP'].
->withExcludeDirectories(array $dirs): self: Specify an array of directory paths relative to the basePath to exclude from scanning during discovery. Defaults to common directories like ['vendor', 'tests', 'storage', 'cache', 'node_modules']. Added directories are merged with defaults.
->withTool(array|string $handler, ?string $name = null, ?string $description = null): self: Manually registers a tool.
->withResource(array|string $handler, string $uri, ?string $name = null, ...): self: Manually registers a resource.
->withPrompt(array|string $handler, ?string $name = null, ?string $description = null): self: Manually registers a prompt.
->withResourceTemplate(array|string $handler, ?string $name = null, ..., string $uriTemplate, ...): self: Manually registers a resource template.
->discover(bool $cache = true): self: Initiates the discovery process. Scans the configured directories for attributes, builds the internal registry of MCP elements, and caches them using the provided cache implementation (unless $cache is false). Note: Manually registered elements are always added to the registry, regardless of discovery or caching.
->run(?string $transport = null): int: Starts the server's main processing loop using the specified transport.
- If $transport is 'stdio' (or null when running in CLI), it uses the StdioTransportHandler to communicate over standard input/output.
- If $transport is 'http' or 'reactphp', it throws an exception, as these transports needs to be integrated into an existing HTTP server loop (see Transports section).
- Returns the exit code (relevant for stdio).

Dependency Injection

The Server relies on a PSR-11 ContainerInterface for two main purposes:

Resolving Server Dependencies: The server itself needs instances of LoggerInterface, CacheInterface, and ConfigurationRepositoryInterface to function (e.g., for logging internal operations, caching discovered elements, reading configuration values).
Resolving Handler Dependencies: When an MCP client calls a tool or reads a resource/prompt that maps to one of your attributed methods or a manually registered handler, the server uses the container to get an instance of the handler's class (e.g., $container->get(MyHandlerClass::class)). This allows your handler classes to use constructor injection for their own dependencies (like database connections, application services, etc.).

Default Behavior (No withContainer Call):

If you do not call ->withContainer(), the server uses its internal PhpMcp\Server\Defaults\BasicContainer. This basic container comes pre-configured with default implementations:

LoggerInterface -> Psr\Log\NullLogger (Logging is effectively disabled)
CacheInterface -> PhpMcp\Server\Defaults\FileCache (writes to ../cache/mcp_cache relative to the package directory)
ConfigurationRepositoryInterface -> PhpMcp\Server\Defaults\ArrayConfigurationRepository (uses built-in default configuration values)

In this default mode, you can use the ->withLogger(), ->withCache(), and ->withConfig() methods to replace these defaults. These methods update the instance used by the server and also update the registration within the internal BasicContainer.

Using a Custom Container (->withContainer(MyContainer $c)):

If you provide your own PSR-11 container instance using ->withContainer(), the responsibility shifts entirely to you:

You MUST ensure your container is configured to provide implementations for LoggerInterface, CacheInterface, and ConfigurationRepositoryInterface. The server will attempt to fetch these using $container->get(...) and will fail if they are not available. Providing a NullLogger for LoggerInterface will keep logging disabled.
Your container will also be used to instantiate your handler classes, so ensure all their dependencies are also properly configured within your container.
When using a custom container, the ->withLogger(), ->withCache(), and ->withConfig() methods on the Server instance become largely ineffective for modifying the dependencies the server actually uses during request processing, as the server will always defer to retrieving these services from your provided container. Configure these services directly in your container's setup.

Using the default BasicContainer is suitable for simple cases. For most applications, providing your own pre-configured PSR-11 container (from your framework or a library like PHP-DI) via ->withContainer() is the recommended approach for proper dependency management.

Configuration

The server's behavior can be customized through a configuration repository implementing PhpMcp\Server\Contracts\ConfigurationRepositoryInterface. You provide this using ->withConfig(). If not provided, a default PhpMcp\Server\Defaults\ArrayConfigurationRepository is used.

Key configuration values (using dot notation) include:

mcp.server.name: (string) Server name for handshake.
mcp.server.version: (string) Server version for handshake.
mcp.protocol_versions: (array) Supported protocol versions (e.g., ['2024-11-05']).
mcp.pagination_limit: (int) Default limit for listing elements.
mcp.capabilities.tools.enabled: (bool) Enable/disable the tools capability.
mcp.capabilities.resources.enabled: (bool) Enable/disable the resources capability.
mcp.capabilities.resources.subscribe: (bool) Enable/disable resource subscriptions.
mcp.capabilities.prompts.enabled: (bool) Enable/disable the prompts capability.
mcp.capabilities.logging.enabled: (bool) Enable/disable the logging/setLevel method.
mcp.cache.ttl: (int) Cache time-to-live in seconds.
mcp.cache.prefix: (string) Prefix for cache related to mcp.
mcp.runtime.log_level: (string) Default log level (used by default logger).

You can create your own implementation of the interface or pass an instance of ArrayConfigurationRepository populated with your overrides to ->withConfig(). If a capability flag (e.g., mcp.capabilities.tools.enabled) is set to false, attempts by a client to use methods related to that capability (e.g., tools/list, tools/call) will result in a "Method not found" error.

Transports

MCP defines how clients and servers exchange JSON-RPC messages. This package provides handlers for common transport mechanisms and allows for custom implementations.

Standard I/O (`stdio`)

The PhpMcp\Server\Transports\StdioTransportHandler handles communication over Standard Input (STDIN) and Standard Output (STDOUT). It uses react/event-loop and react/stream internally for non-blocking I/O, making it suitable for direct integration with clients that manage the server process lifecycle, like Cursor or Claude Desktop when configured to run a command. You activate it by calling $server->run('stdio') or simply $server->run() when executed in a CLI environment.

HTTP + Server-Sent Events (`http`)

The PhpMcp\Server\Transports\HttpTransportHandler implements the standard MCP HTTP binding. It uses Server-Sent Events (SSE) for server-to-client communication and standard HTTP POST requests for client-to-server messages. This handler is not run directly via $server->run('http'). Instead, you must integrate its logic into your own HTTP server built with a framework like Symfony, Laravel, or an asynchronous framework like ReactPHP.

Warning

Server Environment Warning: Standard synchronous PHP web server setups (like PHP's built-in server, Apache/Nginx without concurrent FPM processes, or php artisan serve) typically run one PHP process per request. This model cannot reliably handle the concurrent nature of HTTP+SSE, where one long-running GET request handles the SSE stream while other POST requests arrive to send messages. This will likely cause hangs or failed requests.

To use HTTP+SSE reliably, your PHP application must be served by an environment capable of handling multiple requests concurrently, such as:

Nginx + PHP-FPM or Apache + PHP-FPM (with multiple worker processes configured).
Asynchronous PHP Runtimes like ReactPHP, Amp, Swoole (e.g., via Laravel Octane), RoadRunner (e.g., via Laravel Octane), or FrankenPHP.

Additionally, ensure your web server and PHP-FPM (if used) configurations allow long-running scripts (set_time_limit(0) is recommended in your SSE handler) and do not buffer the text/event-stream response.

Client ID Handling: The server needs a reliable way to associate incoming POST requests with the correct persistent SSE connection state. Relying solely on session cookies can be problematic.

Recommended Approach (Query Parameter):
1. When the SSE connection is established, determine a unique clientId (e.g., session ID or generated UUID).
2. Generate the URL for the POST endpoint (where the client sends messages).
3. Append the clientId as a query parameter to this URL (e.g., /mcp/message?clientId=UNIQUE_ID).
4. Send this complete URL (including the query parameter) to the client via the initial endpoint SSE event.
5. In your HTTP controller handling the POST requests, retrieve the clientId directly from the query parameter ($request->query('clientId')).
6. Pass this explicit clientId to $httpHandler->handleInput(...).

Integration Steps (General):

Configure Server: Create and configure your PhpMcp\Server\Server instance (e.g., $server = Server::make()->withLogger(...)->discover();).
Instantiate Handler: Get an instance of HttpTransportHandler, passing the configured $server instance to its constructor: $httpHandler = new HttpTransportHandler($server); (or use dependency injection configured to do this).
SSE Endpoint: Create an endpoint (e.g., /mcp/sse) for GET requests. Set Content-Type: text/event-stream and keep the connection open.
POST Endpoint: Create an endpoint (e.g., /mcp/message) for POST requests with Content-Type: application/json.
SSE Handler Logic: Determine the clientId, use the $httpHandler, generate the POST URI with the clientId query parameter, call $httpHandler->handleSseConnection(...), and ensure $httpHandler->cleanupClient(...) is called when the connection closes.
POST Handler Logic: Retrieve the clientId from the query parameter, get the raw JSON request body, use the $httpHandler, call $httpHandler->handleInput(...) with the body and clientId, and return an appropriate HTTP response (e.g., 202 Accepted).

ReactPHP HTTP Transport (`reactphp`)

This package includes PhpMcp\Server\Transports\ReactPhpHttpTransportHandler, a concrete transport handler that integrates the core MCP HTTP+SSE logic with the ReactPHP ecosystem. It replaces potentially synchronous or blocking loops (often found in basic integrations of HttpTransportHandler) with ReactPHP's fully asynchronous, non-blocking event loop and stream primitives. Instantiate it by passing your configured Server instance: $reactHandler = new ReactPhpHttpTransportHandler($server);. This enables efficient handling of concurrent SSE connections within a ReactPHP-based application server. See the samples/reactphp_http/server.php example for a practical implementation.

Custom Transports

You can create your own transport handlers if stdio or http don't fit your specific needs (e.g., WebSockets, custom RPC mechanisms). Two main approaches exist:

Implement the Interface: Create a class that implements PhpMcp\Server\Contracts\TransportHandlerInterface. This gives you complete control over the communication lifecycle.
Extend Existing Handlers: Inherit from PhpMcp\Server\Transports\StdioTransportHandler, PhpMcp\Server\Transports\HttpTransportHandler, or PhpMcp\Server\Transports\ReactPhpHttpTransportHandler. Override specific methods to adapt the behavior (e.g., sendResponse, handleSseConnection, cleanupClient). Remember to call the parent constructor correctly if extending HTTP handlers: parent::__construct($server). The ReactPhpHttpTransportHandler serves as a good example of extending HttpTransportHandler.

Examine the source code of the provided handlers to understand the interaction with the Processor and how to manage the request/response flow and client state.

Advanced Usage & Recipes

Here are some examples of how to integrate php-mcp/server with common libraries and frameworks.

Using Custom PSR Implementations

Monolog (PSR-3 Logger):

use Monolog\Logger;
use Monolog\Handler\StreamHandler;
use PhpMcp\Server\Server;

// composer require monolog/monolog
$log = new Logger('mcp-server');
$log->pushHandler(new StreamHandler(__DIR__.'/mcp.log', Logger::DEBUG));

$server = Server::make()
    ->withLogger($log)
    // ... other configurations
    ->discover()
    ->run();

PSR-11 Container (Example with PHP-DI):

use DI\ContainerBuilder;
use PhpMcp\Server\Server;

// composer require php-di/php-di
$containerBuilder = new ContainerBuilder();
// $containerBuilder->addDefinitions(...); // Add your app definitions
$container = $containerBuilder->build();

$server = Server::make()
    ->withContainer($container)
    // ... other configurations
    ->discover()
    ->run();

Fine-grained Configuration: Override default settings by providing a pre-configured ArrayConfigurationRepository:

use PhpMcp\Server\Defaults\ArrayConfigurationRepository;
use PhpMcp\Server\Server;

$configOverrides = [
    'mcp.server.name' => 'My Custom PHP Server',
    'mcp.capabilities.prompts.enabled' => false, // Disable prompts
    'mcp.discovery.directories' => ['src/Api/McpHandlers'], // Scan only specific dir
];

$configRepo = new ArrayConfigurationRepository($configOverrides); 
// Note: This replaces ALL defaults. Merge manually if needed:
// $defaultConfig = new ArrayConfigurationRepository(); // Get defaults
// $mergedConfigData = array_merge_recursive($defaultConfig->all(), $configOverrides);
// $configRepo = new ArrayConfigurationRepository($mergedConfigData);

$server = Server::make()
    ->withConfig($configRepo)
    // Ensure other PSR dependencies are provided if not using defaults
    // ->withLogger(...)->withCache(...)->withContainer(...)
    ->withBasePath(__DIR__)
    ->discover()
    ->run();

HTTP+SSE Integration (Framework Examples)

Symfony Controller Skeleton:

<?php
namespace App\Controller;

use PhpMcp\Server\Transports\HttpTransportHandler;
use Psr\Log\LoggerInterface;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\StreamedResponse;
use Symfony\Component\Routing\Annotation\Route;
use RuntimeException;

class McpController extends AbstractController
{
    private readonly HttpTransportHandler $mcpHandler;
    private readonly LoggerInterface $logger;

    // Inject HttpTransportHandler directly.
    // The Symfony service definition for HttpTransportHandler MUST be configured
    // to receive the fully configured PhpMcp\Server\Server instance as an argument.
    public function __construct(
        private readonly HttpTransportHandler $mcpHandler,
        private readonly LoggerInterface $logger
    ) {}

    #[Route('/mcp', name: 'mcp_post', methods: ['POST'])]
    public function handlePost(Request $request): Response
    {
        $clientId = $request->query('clientId'); 
         if (! $clientId) { 
             // Or: $session = $request->getSession(); $session->start(); $clientId = $session->getId();
             return new Response('Missing clientId', 400);
         }

        if (! $request->isJson()) {
            return new Response('Content-Type must be application/json', 415);
        }
        $content = $request->getContent();
        if (empty($content)) {
            return new Response('Empty request body', 400);
        }

        // Ensure session is started if using session ID
        $session = $request->getSession();
        $session->start(); // Make sure session exists
        $clientId = $session->getId();

        try {
            $this->mcpHandler->handleInput($content, $clientId);
            return new Response(null, 202); // Accepted
        } catch (\JsonException $e) {
            return new Response('Invalid JSON: '.$e->getMessage(), 400);
        } catch (\Throwable $e) {
            $this->logger->error('MCP POST error', ['exception' => $e]);
            return new Response('Internal Server Error', 500);
        }
    }

    #[Route('/mcp/sse', name: 'mcp_sse', methods: ['GET'])]
    public function handleSse(Request $request): StreamedResponse
    {
        // Retrieve/generate clientId (e.g., from session or generate new one)
        $session = $request->getSession(); 
        $session->start(); 
        $clientId = $session->getId();
        // Or: $clientId = 'client_'.bin2hex(random_bytes(16));
        
        $this->logger->info('MCP SSE connection opening', ['client_id' => $clientId]);

        $response = new StreamedResponse(function () use ($clientId, $request) {
            try {
                $postEndpointUri = $this->generateUrl('mcp_post', ['clientId' => $clientId], \Symfony\Component\Routing\Generator\UrlGeneratorInterface::ABSOLUTE_URL);
                
                // Use the handler's method to manage the SSE loop
                $this->mcpHandler->handleSseConnection($clientId, $postEndpointUri);
            } catch (\Throwable $e) {
                    if (! ($e instanceof RuntimeException && str_contains($e->getMessage(), 'disconnected'))) {
                        $this->logger->error('SSE stream loop terminated unexpectedly', ['exception' => $e, 'clientId' => $clientId]);
                    }
            } finally {
                // Ensure cleanup happens when the loop exits
                $this->mcpHandler->cleanupClient($clientId);
                $this->logger->info('SSE connection closed', ['client_id' => $clientId]);
            }
        });

        // Set headers for SSE
        $response->headers->set('Content-Type', 'text/event-stream');
        $response->headers->set('Cache-Control', 'no-cache');
        $response->headers->set('Connection', 'keep-alive');
        $response->headers->set('X-Accel-Buffering', 'no'); // Important for Nginx
        return $response;
    }
}

Resource, Tool, and Prompt Change Notifications

Clients may need to be notified if the available resources, tools, or prompts change after the initial connection and initialize handshake (e.g., due to dynamic configuration changes, file watching, etc.).

When your application detects such a change, retrieve the Registry instance (e.g., via $server->getRegistry() or DI) and call the appropriate method:

$registry->notifyResourceChanged(string $uri): If a specific resource's content changed.
$registry->notifyResourcesListChanged(): If the list of available resources changed.
$registry->notifyToolsListChanged(): If the list of available tools changed.
$registry->notifyPromptsListChanged(): If the list of available prompts changed.

These methods trigger internal notifiers (configurable via set*ChangedNotifier methods on the registry). The active transport handler (especially HttpTransportHandler in its SSE loop) listens for these notifications and sends the corresponding MCP notification (resources/didChange, resources/listChanged, tools/listChanged, prompts/listChanged) to connected clients.

Connecting MCP Clients

You can connect various MCP-compatible clients to servers built with this library. The connection method depends on the transport you are using (stdio or http).

General Principles:

stdio Transport: You typically provide the client with the command needed to execute your server script (e.g., php /path/to/mcp-server.php). The client manages the server process lifecycle.
http Transport: You provide the client with the URL of your SSE endpoint (e.g., http://localhost:8080/mcp/sse). The client connects to this URL, and the server (via the initial endpoint event) tells the client where to send POST requests.

Client-Specific Instructions:

Cursor:

Open your User Settings (Cmd/Ctrl + ,), navigate to the MCP section, or directly edit your .cursor/mcp.json file.

Add an entry under mcpServers:

For stdio:

{
    "mcpServers": {
        "my-php-server-stdio": { // Choose a unique name
            "command": "php",
            "args": [
                "/full/path/to/your/project/mcp-server.php" // Use absolute path
            ]
        }
    }
}

For http: (Check Cursor's documentation for the exact format, likely involves a url field)

{
    "mcpServers": {
        "my-php-server-http": { // Choose a unique name
            "url": "http://localhost:8080/mcp/sse" // Your SSE endpoint URL
        }
    }
}

Claude Desktop:
- Go to Settings -> Connected Apps -> MCP Servers -> Add Server.
- For stdio: Select "Command" type, enter php in the command field, and the absolute path to your mcp-server.php script in the arguments field.
- For http: Select "URL" type and enter the full URL of your SSE endpoint (e.g., http://localhost:8080/mcp/sse).
- (Refer to official Claude Desktop documentation for the most up-to-date instructions.)
Windsurf:
- Connection settings are typically managed through its configuration.
- For stdio: Look for options to define a server using a command and arguments, similar to Cursor.
- For http+sse: Look for options to connect to an MCP server via a URL, providing your SSE endpoint.
- (Refer to official Windsurf documentation for specific details.)

Examples

Working examples demonstrating different setups can be found in the samples/ directory:

samples/php_stdio/: Demonstrates a basic server using the stdio transport, suitable for direct command-line execution by clients.
samples/php_http/: Provides a basic example of integrating with a synchronous PHP HTTP server (e.g., using PHP's built-in server or Apache/Nginx with PHP-FPM). Note: Requires careful handling of request lifecycles and SSE for full functionality.
samples/reactphp_http/: Shows how to integrate the ReactPhpHttpTransportHandler with ReactPHP to create an asynchronous HTTP+SSE server.

Testing

This package uses Pest for testing.

Install development dependencies:
```
composer install --dev
```
Run the test suite:
```
composer test
```
Run tests with code coverage reporting (requires Xdebug):
```
composer test:coverage
```

Contributing

Please see CONTRIBUTING.md for details (if it exists), but generally:

Report bugs or suggest features via GitHub Issues.
Submit pull requests for improvements. Please ensure tests pass and code style is maintained.

License

The MIT License (MIT). Please see License File for more information.

Support & Feedback

Please open an issue on the GitHub repository for bugs, questions, or feedback.

Name		Name	Last commit message	Last commit date
.github/workflows		.github/workflows
samples		samples
src		src
tests		tests
.gitignore		.gitignore
CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
README.md		README.md
composer.json		composer.json
phpunit.xml		phpunit.xml

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PHP MCP Server

Introduction

Key Features

Requirements

Installation

Getting Started: A Simple stdio Server

Core Concepts

Attributes for Discovery

#[McpTool]

#[McpResource]

#[McpResourceTemplate]

#[McpPrompt]

The Server Fluent Interface

Dependency Injection

Configuration

Transports

Standard I/O (stdio)

HTTP + Server-Sent Events (http)

ReactPHP HTTP Transport (reactphp)

Custom Transports

Advanced Usage & Recipes

Using Custom PSR Implementations

HTTP+SSE Integration (Framework Examples)

Resource, Tool, and Prompt Change Notifications

Connecting MCP Clients

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Getting Started: A Simple `stdio` Server

`#[McpTool]`

`#[McpResource]`

`#[McpResourceTemplate]`

`#[McpPrompt]`

The `Server` Fluent Interface

Standard I/O (`stdio`)

HTTP + Server-Sent Events (`http`)

ReactPHP HTTP Transport (`reactphp`)