[Client] Feat: Implement MCP client component (#192)

* feat(client): add complete MCP client SDK with STDIO and HTTP transports

Add Client, Builder, ClientProtocol, ClientSession, and transport
implementations for communicating with MCP servers. Supports tools, resources, prompts, and real-time progress/logging notifications.

* refactor(examples): reorganize examples into server/ and client/ folders

* feat: add SamplingRequestHandler for handling server sampling requests

* feat: add setLoggingLevel method to control server logging verbosity

* refactor: make progress token dependent on request ID

* docs: Update server IP in usage instructions and add notes on sampling server requirements.

* feat: add complete() method for completion/complete requests

* refactor: properly parse and type initialize result

* refactor: standardize method names

* fix: revert changes to server related components

* fix: revert changes to server related components

* refactor: Restructure client transports and handlers into dedicated namespaces.

* fix: cs and php-stan errors fixes(partial)

* feat: Refactor request handlers to return `Response` or `Error` objects directly, adding a `SamplingException` and error logging for sampling requests.

* feat: Replace `ClientTransportInterface` with `TransportInterface` and move response result deserialization to client methods.

* refactor: remove redundant timeout check for intialize on transports

The processFiber that executes per tick while fiber is suspended already handles timeouts while waiting

* feat: broaden symfony/http-client dependency to support Symfony 5.4 to 8.0

* Update examples/client/README.md

Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>

* Update examples/client/README.md

Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>

* refactor: remove outgoing message queue from session and simplify transport send method to directly dispatch messages.

* refactor: Replace ClientSession with ClientState for clearer intent on runtime state management

* refactor: rename connectAndInitialize to connect for consistency

* chore: cs fix

* chore: use SamplingCallbackInterface instead of a closure for sampling request handler

---------

Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>
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examples/client/README.md Normal file
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# Client Examples
These examples demonstrate how to use the MCP PHP Client SDK.
## STDIO Client
Connects to an MCP server running as a child process:
```bash
php examples/client/stdio_discovery_calculator.php
```
## HTTP Client
Connects to an MCP server over HTTP:
```bash
# First, start an HTTP server
php -S localhost:8000 examples/server/discovery-calculator/server.php
# Then run the client
php examples/client/http_discovery_calculator.php
```
## Requirements
All examples require the server examples to be available. The STDIO examples spawn the server process, while the HTTP examples connect to a running HTTP server.

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<?php
/**
* HTTP Client Communication Example.
*
* This example demonstrates server-to-client communication over HTTP:
* - Logging notifications
* - Progress notifications (via SSE streaming)
* - Sampling requests (mocked LLM response)
*
* Usage:
* 1. Start the server: php -S 127.0.0.1:8000 examples/server/client-communication/server.php
* 2. Run this script: php examples/client/http_client_communication.php
*
* Note: PHP's built-in server works for listing tools, calling tools, and receiving
* progress/logging notifications. However, sampling requires a concurrent-capable server
* (e.g., Symfony CLI, PHP-FPM) since the server must process the client's sampling
* response while the original tool request is still pending.
*
* Eg. symfony serve --passthru=examples/server/client-communication/server.php --no-tls
*/
declare(strict_types=1);
/*
* This file is part of the official PHP MCP SDK.
*
* A collaboration between Symfony and the PHP Foundation.
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
require_once __DIR__.'/../../vendor/autoload.php';
use Mcp\Client;
use Mcp\Client\Handler\Notification\LoggingNotificationHandler;
use Mcp\Client\Handler\Request\SamplingCallbackInterface;
use Mcp\Client\Handler\Request\SamplingRequestHandler;
use Mcp\Client\Transport\HttpTransport;
use Mcp\Schema\ClientCapabilities;
use Mcp\Schema\Content\TextContent;
use Mcp\Schema\Enum\Role;
use Mcp\Schema\Notification\LoggingMessageNotification;
use Mcp\Schema\Request\CreateSamplingMessageRequest;
use Mcp\Schema\Result\CreateSamplingMessageResult;
$endpoint = 'http://127.0.0.1:8000';
$loggingNotificationHandler = new LoggingNotificationHandler(static function (LoggingMessageNotification $n) {
echo "[LOG {$n->level->value}] {$n->data}\n";
});
$samplingRequestHandler = new SamplingRequestHandler(new class implements SamplingCallbackInterface {
public function __invoke(CreateSamplingMessageRequest $request): CreateSamplingMessageResult
{
echo "[SAMPLING] Server requested LLM sampling (max {$request->maxTokens} tokens)\n";
$mockResponse = 'Based on the incident analysis, I recommend: 1) Activate the on-call team, '.
'2) Isolate affected systems, 3) Begin root cause analysis, 4) Prepare stakeholder communication.';
return new CreateSamplingMessageResult(
role: Role::Assistant,
content: new TextContent($mockResponse),
model: 'mock-gpt-4',
stopReason: 'end_turn',
);
}
});
$client = Client::builder()
->setClientInfo('HTTP Client Communication Test', '1.0.0')
->setInitTimeout(30)
->setRequestTimeout(120)
->setCapabilities(new ClientCapabilities(sampling: true))
->addNotificationHandler($loggingNotificationHandler)
->addRequestHandler($samplingRequestHandler)
->build();
$transport = new HttpTransport(endpoint: $endpoint);
try {
echo "Connecting to MCP server at {$endpoint}...\n";
$client->connect($transport);
$serverInfo = $client->getServerInfo();
echo 'Connected to: '.($serverInfo->name ?? 'unknown')."\n\n";
echo "Available tools:\n";
$toolsResult = $client->listTools();
foreach ($toolsResult->tools as $tool) {
echo " - {$tool->name}\n";
}
echo "\n";
echo "Calling 'run_dataset_quality_checks'...\n\n";
$result = $client->callTool(
name: 'run_dataset_quality_checks',
arguments: ['dataset' => 'sales_transactions_q4'],
onProgress: static function (float $progress, ?float $total, ?string $message) {
$percent = $total > 0 ? round(($progress / $total) * 100) : '?';
echo "[PROGRESS {$percent}%] {$message}\n";
}
);
echo "\nResult:\n";
foreach ($result->content as $content) {
if ($content instanceof TextContent) {
echo $content->text."\n";
}
}
echo "\nCalling 'coordinate_incident_response'...\n\n";
$result = $client->callTool(
name: 'coordinate_incident_response',
arguments: ['incidentTitle' => 'Database connection pool exhausted'],
onProgress: static function (float $progress, ?float $total, ?string $message) {
$percent = $total > 0 ? round(($progress / $total) * 100) : '?';
echo "[PROGRESS {$percent}%] {$message}\n";
}
);
echo "\nResult:\n";
foreach ($result->content as $content) {
if ($content instanceof TextContent) {
echo $content->text."\n";
}
}
} catch (Throwable $e) {
echo "Error: {$e->getMessage()}\n";
echo $e->getTraceAsString()."\n";
} finally {
$client->disconnect();
}

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<?php
/**
* HTTP Client Example.
*
* This example demonstrates how to use the MCP client with an HTTP transport
* to communicate with a remote MCP server over HTTP.
*
* Usage: php examples/client/http_discovery_calculator.php
*
* Before running, start an HTTP MCP server:
* php -S localhost:8080 examples/server/http-discovery-calculator/server.php
*/
declare(strict_types=1);
/*
* This file is part of the official PHP MCP SDK.
*
* A collaboration between Symfony and the PHP Foundation.
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
require_once __DIR__.'/../../vendor/autoload.php';
use Mcp\Client;
use Mcp\Client\Transport\HttpTransport;
$endpoint = 'http://localhost:8000';
$client = Client::builder()
->setClientInfo('HTTP Example Client', '1.0.0')
->setInitTimeout(30)
->setRequestTimeout(60)
->build();
$transport = new HttpTransport($endpoint);
try {
echo "Connecting to MCP server at {$endpoint}...\n";
$client->connect($transport);
echo "Connected! Server info:\n";
$serverInfo = $client->getServerInfo();
echo ' Name: '.($serverInfo->name ?? 'unknown')."\n";
echo ' Version: '.($serverInfo->version ?? 'unknown')."\n\n";
echo "Available tools:\n";
$toolsResult = $client->listTools();
foreach ($toolsResult->tools as $tool) {
echo " - {$tool->name}: {$tool->description}\n";
}
echo "\n";
echo "Available resources:\n";
$resourcesResult = $client->listResources();
foreach ($resourcesResult->resources as $resource) {
echo " - {$resource->uri}: {$resource->name}\n";
}
echo "\n";
echo "Available prompts:\n";
$promptsResult = $client->listPrompts();
foreach ($promptsResult->prompts as $prompt) {
echo " - {$prompt->name}: {$prompt->description}\n";
}
echo "\n";
} catch (Throwable $e) {
echo "Error: {$e->getMessage()}\n";
echo $e->getTraceAsString()."\n";
} finally {
echo "Disconnecting...\n";
$client->disconnect();
echo "Done.\n";
}

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<?php
/**
* STDIO Client Communication Example.
*
* This example demonstrates server-to-client communication:
* - Logging notifications
* - Progress notifications
* - Sampling requests (mocked LLM response)
*
* Usage: php examples/client/stdio_client_communication.php
*/
declare(strict_types=1);
/*
* This file is part of the official PHP MCP SDK.
*
* A collaboration between Symfony and the PHP Foundation.
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
require_once __DIR__.'/../../vendor/autoload.php';
use Mcp\Client;
use Mcp\Client\Handler\Notification\LoggingNotificationHandler;
use Mcp\Client\Handler\Request\SamplingCallbackInterface;
use Mcp\Client\Handler\Request\SamplingRequestHandler;
use Mcp\Client\Transport\StdioTransport;
use Mcp\Schema\ClientCapabilities;
use Mcp\Schema\Content\TextContent;
use Mcp\Schema\Enum\Role;
use Mcp\Schema\Notification\LoggingMessageNotification;
use Mcp\Schema\Request\CreateSamplingMessageRequest;
use Mcp\Schema\Result\CreateSamplingMessageResult;
$loggingNotificationHandler = new LoggingNotificationHandler(static function (LoggingMessageNotification $n) {
echo "[LOG {$n->level->value}] {$n->data}\n";
});
$samplingRequestHandler = new SamplingRequestHandler(new class implements SamplingCallbackInterface {
public function __invoke(CreateSamplingMessageRequest $request): CreateSamplingMessageResult
{
echo "[SAMPLING] Server requested LLM sampling (max {$request->maxTokens} tokens)\n";
$mockResponse = 'Based on the incident analysis, I recommend: 1) Activate the on-call team, '.
'2) Isolate affected systems, 3) Begin root cause analysis, 4) Prepare stakeholder communication.';
return new CreateSamplingMessageResult(
role: Role::Assistant,
content: new TextContent($mockResponse),
model: 'mock-gpt-4',
stopReason: 'end_turn',
);
}
});
$client = Client::builder()
->setClientInfo('STDIO Client Communication Test', '1.0.0')
->setInitTimeout(30)
->setRequestTimeout(120)
->setCapabilities(new ClientCapabilities(sampling: true))
->addNotificationHandler($loggingNotificationHandler)
->addRequestHandler($samplingRequestHandler)
->build();
$transport = new StdioTransport(
command: 'php',
args: [__DIR__.'/../server/client-communication/server.php'],
);
try {
echo "Connecting to MCP server...\n";
$client->connect($transport);
$serverInfo = $client->getServerInfo();
echo 'Connected to: '.($serverInfo->name ?? 'unknown')."\n\n";
echo "Available tools:\n";
$toolsResult = $client->listTools();
foreach ($toolsResult->tools as $tool) {
echo " - {$tool->name}\n";
}
echo "\n";
echo "Calling 'run_dataset_quality_checks'...\n\n";
$result = $client->callTool(
name: 'run_dataset_quality_checks',
arguments: ['dataset' => 'customer_orders_2024'],
onProgress: static function (float $progress, ?float $total, ?string $message) {
$percent = $total > 0 ? round(($progress / $total) * 100) : '?';
echo "[PROGRESS {$percent}%] {$message}\n";
}
);
echo "\nResult:\n";
foreach ($result->content as $content) {
if ($content instanceof TextContent) {
echo $content->text."\n";
}
}
echo "\nCalling 'coordinate_incident_response'...\n\n";
$result = $client->callTool(
name: 'coordinate_incident_response',
arguments: ['incidentTitle' => 'Database connection pool exhausted'],
onProgress: static function (float $progress, ?float $total, ?string $message) {
$percent = $total > 0 ? round(($progress / $total) * 100) : '?';
echo "[PROGRESS {$percent}%] {$message}\n";
}
);
echo "\nResult:\n";
foreach ($result->content as $content) {
if ($content instanceof TextContent) {
echo $content->text."\n";
}
}
} catch (Throwable $e) {
echo "Error: {$e->getMessage()}\n";
echo $e->getTraceAsString()."\n";
} finally {
$client->disconnect();
}

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<?php
/**
* Simple STDIO Client Example.
*
* This example demonstrates how to use the MCP client with a STDIO transport
* to communicate with an MCP server running as a child process.
*
* Usage: php examples/client/stdio_discovery_calculator.php
*/
declare(strict_types=1);
/*
* This file is part of the official PHP MCP SDK.
*
* A collaboration between Symfony and the PHP Foundation.
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
require_once __DIR__.'/../../vendor/autoload.php';
use Mcp\Client;
use Mcp\Client\Transport\StdioTransport;
use Mcp\Schema\Content\TextContent;
use Mcp\Schema\Content\TextResourceContents;
$client = Client::builder()
->setClientInfo('STDIO Example Client', '1.0.0')
->setInitTimeout(30)
->setRequestTimeout(60)
->build();
$transport = new StdioTransport(
command: 'php',
args: [__DIR__.'/../server/discovery-calculator/server.php'],
);
try {
echo "Connecting to MCP server...\n";
$client->connect($transport);
echo "Connected! Server info:\n";
$serverInfo = $client->getServerInfo();
echo ' Name: '.($serverInfo->name ?? 'unknown')."\n";
echo ' Version: '.($serverInfo->version ?? 'unknown')."\n\n";
echo "Available tools:\n";
$toolsResult = $client->listTools();
foreach ($toolsResult->tools as $tool) {
echo " - {$tool->name}: {$tool->description}\n";
}
echo "\n";
echo "Calling 'calculate' tool with a=5, b=3, operation='add'...\n";
$result = $client->callTool('calculate', ['a' => 5, 'b' => 3, 'operation' => 'add']);
echo 'Result: ';
foreach ($result->content as $content) {
if ($content instanceof TextContent) {
echo $content->text;
}
}
echo "\n\n";
echo "Available resources:\n";
$resourcesResult = $client->listResources();
foreach ($resourcesResult->resources as $resource) {
echo " - {$resource->uri}: {$resource->name}\n";
}
echo "\n";
echo "Reading resource 'config://calculator/settings'...\n";
$resourceContent = $client->readResource('config://calculator/settings');
foreach ($resourceContent->contents as $content) {
if ($content instanceof TextResourceContents) {
echo ' Content: '.$content->text."\n";
echo ' Mimetype: '.$content->mimeType."\n";
}
}
} catch (Throwable $e) {
echo "Error: {$e->getMessage()}\n";
echo $e->getTraceAsString()."\n";
} finally {
echo "Disconnecting...\n";
$client->disconnect();
echo "Done.\n";
}

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@ -8,10 +8,10 @@ The bootstrapping of the example will choose the used transport based on the SAP
For running an example, you execute the `server.php` like this:
```bash
# For using the STDIO transport:
php examples/discovery-calculator/server.php
php examples/server/discovery-calculator/server.php
# For using the Streamable HTTP transport:
php -S localhost:8000 examples/discovery-userprofile/server.php
php -S localhost:8000 examples/server/discovery-userprofile/server.php
```
You will see debug outputs to help you understand what is happening.
@ -19,7 +19,7 @@ You will see debug outputs to help you understand what is happening.
Run with Inspector:
```bash
npx @modelcontextprotocol/inspector php examples/discovery-calculator/server.php
npx @modelcontextprotocol/inspector php examples/server/discovery-calculator/server.php
```
## Debugging
@ -30,5 +30,5 @@ directory.
With the Inspector you can set the environment variables like this:
```bash
npx @modelcontextprotocol/inspector -e DEBUG=1 -e FILE_LOG=1 php examples/discovery-calculator/server.php
npx @modelcontextprotocol/inspector -e DEBUG=1 -e FILE_LOG=1 php examples/server/discovery-calculator/server.php
```

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@ -55,7 +55,7 @@ function shutdown(ResponseInterface|int $result): never
function logger(): LoggerInterface
{
return new class extends AbstractLogger {
public function log($level, Stringable|string $message, array $context = []): void
public function log($level, string|Stringable $message, array $context = []): void
{
$debug = $_SERVER['DEBUG'] ?? false;

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@ -1,4 +1,3 @@
#!/usr/bin/env php
<?php
/*