php-sdk/examples/client/stdio_elicitation.php
Johannes Wachter e4a8a224ff
[Client] Add client-side elicitation support (#371)
* [Client] Add client-side elicitation support

The SDK could send elicitation/create requests from a server tool via
ClientGateway::elicit(), but the client could not receive them: there was
no request handler, and ElicitRequest was not registered in MessageFactory,
so incoming elicitation/create messages failed to parse.

This adds the client half, mirroring the existing Sampling pattern:

- Register ElicitRequest in MessageFactory so elicitation/create parses.
- ElicitationRequestHandler wraps a user callback and returns an
  ElicitResult (accept/decline/cancel) or an Error.
- ElicitationCallbackInterface defines the callback contract.
- ElicitationException forwards a specific message to the server; any
  other throwable returns a generic error.

Includes unit tests, a runnable client example against the elicitation
demo server, and client docs/README updates.

* [Client] Simplify elicitation example labelFor() per review

Type the parameter as AbstractSchemaDefinition and read ->title directly
instead of matching on each concrete definition type. title is a required
non-null string on the base class, so the match and the $name fallback were
redundant.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
2026-07-14 23:55:06 +02:00

144 lines
4.8 KiB
PHP

<?php
/*
* 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.
*/
/**
* STDIO Client Elicitation Example.
*
* This example demonstrates how a client responds to server-initiated
* elicitation/create requests. The server's tools ask the user for additional
* information mid-execution; the client below prompts interactively on STDIN
* and accepts defaults when the user presses Enter.
*
* Run against the elicitation demo server:
* php examples/client/stdio_elicitation.php
*/
require_once __DIR__.'/../../vendor/autoload.php';
use Mcp\Client;
use Mcp\Client\Handler\Request\ElicitationCallbackInterface;
use Mcp\Client\Handler\Request\ElicitationRequestHandler;
use Mcp\Client\Transport\StdioTransport;
use Mcp\Schema\ClientCapabilities;
use Mcp\Schema\Content\TextContent;
use Mcp\Schema\Elicitation\AbstractSchemaDefinition;
use Mcp\Schema\Elicitation\BooleanSchemaDefinition;
use Mcp\Schema\Elicitation\EnumSchemaDefinition;
use Mcp\Schema\Elicitation\NumberSchemaDefinition;
use Mcp\Schema\Elicitation\StringSchemaDefinition;
use Mcp\Schema\Enum\ElicitAction;
use Mcp\Schema\Request\ElicitRequest;
use Mcp\Schema\Result\ElicitResult;
$elicitationRequestHandler = new ElicitationRequestHandler(new class implements ElicitationCallbackInterface {
public function __invoke(ElicitRequest $request): ElicitResult
{
echo "\n[ELICIT] {$request->message}\n";
$content = [];
foreach ($request->requestedSchema->properties as $name => $definition) {
$default = $this->defaultFor($definition);
$label = $this->labelFor($definition);
if (null !== $default) {
$display = is_bool($default) ? ($default ? 'true' : 'false') : (string) $default;
echo " {$label} [{$display}]: ";
} else {
echo " {$label}: ";
}
$rawInput = fgets(\STDIN);
$input = false === $rawInput ? '' : trim($rawInput);
$value = '' === $input ? $default : $this->cast($definition, $input);
$content[$name] = $value;
}
return new ElicitResult(ElicitAction::Accept, $content);
}
private function defaultFor(object $definition): mixed
{
return match (true) {
$definition instanceof EnumSchemaDefinition => $definition->default ?? $definition->enum[0],
$definition instanceof NumberSchemaDefinition => $definition->default ?? $definition->minimum ?? ($definition->integerOnly ? 1 : 1.0),
$definition instanceof BooleanSchemaDefinition => $definition->default ?? false,
$definition instanceof StringSchemaDefinition => $definition->default ?? ('date' === $definition->format ? date('Y-m-d') : ''),
default => null,
};
}
private function labelFor(AbstractSchemaDefinition $definition): string
{
return $definition->title;
}
private function cast(object $definition, string $input): mixed
{
return match (true) {
$definition instanceof BooleanSchemaDefinition => filter_var($input, \FILTER_VALIDATE_BOOLEAN),
$definition instanceof NumberSchemaDefinition => $definition->integerOnly ? (int) $input : (float) $input,
default => $input,
};
}
});
$client = Client::builder()
->setClientInfo('STDIO Elicitation Test', '1.0.0')
->setInitTimeout(30)
->setRequestTimeout(120)
->setCapabilities(new ClientCapabilities(elicitation: true))
->addRequestHandler($elicitationRequestHandler)
->build();
$transport = new StdioTransport(
command: 'php',
args: [__DIR__.'/../server/elicitation/server.php'],
);
try {
echo "Connecting to MCP server...\n";
$client->connect($transport);
$serverInfo = $client->getServerInfo();
echo 'Connected to: '.($serverInfo->name ?? 'unknown')."\n\n";
echo "Calling 'book_restaurant'...\n";
$result = $client->callTool(
name: 'book_restaurant',
arguments: ['restaurantName' => 'The Test Kitchen'],
);
echo "\nResult:\n";
foreach ($result->content as $content) {
if ($content instanceof TextContent) {
echo $content->text."\n";
}
}
echo "\nCalling 'confirm_action'...\n";
$result = $client->callTool(
name: 'confirm_action',
arguments: ['actionDescription' => 'Delete all temporary files'],
);
echo "\nResult:\n";
foreach ($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();
}