Transports

Transports handle the communication layer between client and server.

STDIO Transport

Spawns a server process and communicates via standard input/output:

use Mcp\Client\Transport\StdioTransport;

$transport = new StdioTransport(
    command: 'php',
    args: ['/path/to/server.php'],
    cwd: '/working/directory',     // Optional working directory
    env: ['KEY' => 'value'],       // Optional environment variables
);

Parameters: - command (string): The command to execute - args (array): Command arguments - cwd (string|null): Working directory for the process - env (array|null): Environment variables - logger (LoggerInterface|null): Optional PSR-3 logger - maxBufferSize (int): Maximum buffered bytes per message before the transport gives up

HTTP Transport

Communicates with remote MCP servers over HTTP:

use Mcp\Client\Transport\HttpTransport;

$transport = new HttpTransport(
    endpoint: 'http://localhost:8000',
    headers: ['Authorization' => 'Bearer token'],
);

Parameters: - endpoint (string): The MCP server URL - headers (array): Additional HTTP headers - httpClient (ClientInterface|null): PSR-18 HTTP client (auto-discovered) - requestFactory (RequestFactoryInterface|null): PSR-17 request factory (auto-discovered) - streamFactory (StreamFactoryInterface|null): PSR-17 stream factory (auto-discovered) - logger (LoggerInterface|null): Optional PSR-3 logger - maxSseBufferBytes (int): Maximum buffered bytes for a streamed SSE response

PSR-18 Auto-Discovery:

The transport automatically discovers PSR-18 HTTP clients from: - php-http/guzzle7-adapter - php-http/curl-client - symfony/http-client - And other PSR-18 compatible implementations

# Install any PSR-18 client - discovery works automatically
composer require php-http/guzzle7-adapter