A PHP SDK for the Model Context Protocol (MCP), allowing seamless integration between applications and Large Language Models (LLMs).
- PHP 8.1 or higher
- Composer
composer require elliottlawson/mcp-php-sdkThe Model Context Protocol (MCP) is an open standard for connecting large language models (LLMs) to applications, APIs, and external data sources. This PHP SDK provides a structured implementation for PHP applications to integrate with MCP.
The Protocol layer handles the core MCP message format and communication patterns:
McpMessage: Represents JSON-RPC 2.0 messages used in MCPProtocol: Handles message framing, request-response linking, and pattern registration
The Transport layer defines how messages are sent and received:
TransportInterface: Defines the contract for all transport implementationsStdioTransport: Implementation for command-line applications using standard input/outputSseTransport: Implementation for web applications using Server-Sent Events (SSE)
Resources are data sources that LLMs can access:
Resource: Represents a data sourceResourceTemplate: Handles URI templates and pattern matchingResourceContent: Represents the content of a resource
Tools enable LLMs to execute code and produce side effects:
Tool: Represents a tool definitionToolResult: Encapsulates the result of a tool execution
Prompts define reusable templates for LLM interactions:
Prompt: Represents a prompt definitionPromptArgument: Defines arguments for promptsPromptResult: Represents the result of a prompt execution
The server components tie everything together:
McpServer: The main server class that manages connections, resources, tools, and promptsServerCapabilities: Defines the capabilities of the server
<?php
require __DIR__ . '/vendor/autoload.php';
use ElliottLawson\McpPhpSdk\Server\McpServer;
use ElliottLawson\McpPhpSdk\Server\ServerCapabilities;
use ElliottLawson\McpPhpSdk\Transport\StdioTransport;
// Create server capabilities
$capabilities = ServerCapabilities::create()
->withResources(true)
->withTools(true);
// Create an MCP server
$server = new McpServer([
'name' => 'Example MCP Server',
'version' => '1.0.0',
'capabilities' => $capabilities
]);
// Register a simple echo resource
$server->resource(
'echo',
'echo://{message}',
function (string $uri, array $params) {
return [
'contents' => [
[
'uri' => $uri,
'text' => "You said: {$params['message']}"
]
]
];
}
);
// Register a calculator tool
$server->tool(
'calculator',
[
'type' => 'object',
'properties' => [
'operation' => ['type' => 'string', 'enum' => ['add', 'subtract', 'multiply', 'divide']],
'a' => ['type' => 'number'],
'b' => ['type' => 'number']
],
'required' => ['operation', 'a', 'b']
],
function (array $params) {
$a = $params['a'];
$b = $params['b'];
switch ($params['operation']) {
case 'add':
$result = $a + $b;
break;
case 'subtract':
$result = $a - $b;
break;
case 'multiply':
$result = $a * $b;
break;
case 'divide':
if ($b === 0) {
return [
'content' => [['type' => 'text', 'text' => 'Cannot divide by zero']],
'isError' => true
];
}
$result = $a / $b;
break;
default:
return [
'content' => [['type' => 'text', 'text' => 'Unknown operation']],
'isError' => true
];
}
return [
'content' => [
['type' => 'text', 'text' => "Result: $result"]
]
];
}
);
// Start the server with stdio transport
try {
$transport = new StdioTransport();
$server->connect($transport);
// The server will now run until the process is terminated
} catch (\Throwable $e) {
echo "Error: " . $e->getMessage() . PHP_EOL;
exit(1);
}See the examples directory for a complete HTTP/SSE server implementation.
Resources represent data sources that can be accessed by LLMs. To register a resource:
$server->resource(
'name', // The resource name
'uri://{pattern}', // The URI pattern (with placeholders)
function (string $uri, array $params) {
// Handler function that returns resource content
return [
'contents' => [
[
'uri' => $uri,
'text' => 'Content goes here'
// Can also include 'mimeType' for non-text content
]
]
];
}
);Tools enable LLMs to perform actions and have side effects. To register a tool:
$server->tool(
'name', // The tool name
[ // The parameter schema (JSON Schema format)
'type' => 'object',
'properties' => [
'param1' => ['type' => 'string'],
'param2' => ['type' => 'number']
],
'required' => ['param1']
],
function (array $params) {
// Handler function that executes the tool
return [
'content' => [
['type' => 'text', 'text' => 'Result of the tool execution']
// Can include other content types as needed
]
];
}
);Prompts define reusable templates for LLM interactions. To register a prompt:
$server->prompt(
'name', // The prompt name
[ // The parameter schema (JSON Schema format)
'type' => 'object',
'properties' => [
'param1' => ['type' => 'string'],
'param2' => ['type' => 'number']
],
'required' => ['param1']
],
function (array $params) {
// Handler function that generates the prompt
return [
'messages' => [
['role' => 'system', 'content' => 'You are a helpful assistant.'],
['role' => 'user', 'content' => "The user asked about: {$params['param1']}"]
],
'description' => 'A helpful prompt about ' . $params['param1']
];
}
);The SDK includes several examples in the examples directory:
basic-server.php: A simple CLI-based MCP serverhttp-server.php: An HTTP server with SSE transportprompts-server.php: A server demonstrating the prompts feature
To run the basic server:
php examples/basic-server.phpTo run the HTTP server:
php -S localhost:8080 examples/http-server.phpThen visit http://localhost:8080 in your browser.
Contributions are welcome! Please feel free to submit a Pull Request.
This project is licensed under the MIT License.