capabilities.md

Tools, resources & prompts

Once connected, everything the server exposes is reachable through the client: list what is there, then call it. Each list method returns the server's own descriptions and schemas, so a generic client can build its UI from them.

Working with Tools

Listing Tools

$toolsResult = $client->listTools();

foreach ($toolsResult->tools as $tool) {
    echo "- {$tool->name}: {$tool->description}\n";
}

// Handle pagination
if ($toolsResult->nextCursor) {
    $moreTools = $client->listTools($toolsResult->nextCursor);
}

Calling Tools

use Mcp\Schema\Content\TextContent;

$result = $client->callTool(
    name: 'calculate',
    arguments: ['a' => 5, 'b' => 3, 'operation' => 'add'],
);

// Access results
foreach ($result->content as $content) {
    if ($content instanceof TextContent) {
        echo $content->text;
    }
}

Progress Notifications

Hook into tool execution progress (if server supports it):

$result = $client->callTool(
    name: 'long_running_task',
    arguments: ['data' => 'large_dataset'],
    onProgress: static function (float $progress, ?float $total, ?string $message) {
        $percent = $total > 0 ? round(($progress / $total) * 100) : 0;
        echo "Progress: {$percent}% - {$message}\n";
    }
);

!!! note Progress notifications are only received if the server sends them. The callback will not be invoked if the server doesn't support or send progress updates.

Working with Resources

Listing Resources

$resourcesResult = $client->listResources();

foreach ($resourcesResult->resources as $resource) {
    echo "- {$resource->uri}: {$resource->name}\n";
}

Listing Resource Templates

$templatesResult = $client->listResourceTemplates();

foreach ($templatesResult->resourceTemplates as $template) {
    echo "- {$template->uriTemplate}: {$template->name}\n";
}

Reading Resources

use Mcp\Schema\Content\{TextResourceContents, BlobResourceContents};

$resourceResult = $client->readResource('config://app/settings');

foreach ($resourceResult->contents as $content) {
    if ($content instanceof TextResourceContents) {
        echo "Text: {$content->text}\n";
    } elseif ($content instanceof BlobResourceContents) {
        echo "Binary data (base64): {$content->blob}\n";
    }
}

Resources also support progress notifications:

$result = $client->readResource(
    uri: 'file://large-file.bin',
    onProgress: static function (float $progress, ?float $total, ?string $message) {
        echo "Reading: {$progress}/{$total} bytes\n";
    }
);

Working with Prompts

Listing Prompts

$promptsResult = $client->listPrompts();

foreach ($promptsResult->prompts as $prompt) {
    echo "- {$prompt->name}: {$prompt->description}\n";
}

Getting Prompts

$promptResult = $client->getPrompt(
    name: 'code_review',
    arguments: ['language' => 'php', 'code' => '...'],
);

foreach ($promptResult->messages as $message) {
    echo "{$message->role->value}: {$message->content->text}\n";
}

Prompts also support progress notifications:

$result = $client->getPrompt(
    name: 'generate_report',
    arguments: ['topic' => 'quarterly_analysis'],
    onProgress: static function (float $progress, ?float $total, ?string $message) {
        echo "Generating: {$message}\n";
    }
);

Requesting Completions

Request auto-completion suggestions for prompt or resource arguments:

use Mcp\Schema\PromptReference;

$completionResult = $client->complete(
    ref: new PromptReference('code_review'),
    argument: ['name' => 'language', 'value' => 'ph'],
);

foreach ($completionResult->values as $value) {
    echo "Suggestion: {$value}\n";
}