Claude API — PHP

Note: The PHP SDK is the official Anthropic SDK for PHP. Tool runner and Agent SDK are not available. Bedrock, Vertex AI, and Foundry clients are supported.

Installation

composer require "anthropic-ai/sdk"

Client Initialization

use Anthropic\Client;

// Using API key from environment variable
$client = new Client(apiKey: getenv("ANTHROPIC_API_KEY"));

Amazon Bedrock

use Anthropic\Bedrock;

// Constructor is private — use the static factory. Reads AWS credentials from env.
$client = Bedrock\Client::fromEnvironment(region: 'us-east-1');

Google Vertex AI

use Anthropic\Vertex;

// Constructor is private. Parameter is `location`, not `region`.
$client = Vertex\Client::fromEnvironment(
    location: 'us-east5',
    projectId: 'my-project-id',
);

Anthropic Foundry

use Anthropic\Foundry;

// Constructor is private. baseUrl or resource is required.
$client = Foundry\Client::withCredentials(
    authToken: getenv('ANTHROPIC_FOUNDRY_AUTH_TOKEN'),
    baseUrl: 'https://<resource>.services.ai.azure.com/anthropic',
);

Basic Message Request

$message = $client->messages->create(
    model: '{{OPUS_ID}}',
    maxTokens: 16000,
    messages: [
        ['role' => 'user', 'content' => 'What is the capital of France?'],
    ],
);

// content is an array of polymorphic blocks (TextBlock, ToolUseBlock,
// ThinkingBlock). Accessing ->text on content[0] without checking the block
// type will throw if the first block is not a TextBlock (e.g., when extended
// thinking is enabled and a ThinkingBlock comes first). Always guard:
foreach ($message->content as $block) {
    if ($block->type === 'text') {
        echo $block->text;
    }
}

If you only want the first text block:

foreach ($message->content as $block) {
    if ($block->type === 'text') {
        echo $block->text;
        break;
    }
}

Streaming

Requires SDK v0.5.0+. v0.4.0 and earlier used a single $params array; calling with named parameters throws Unknown named parameter $model. Upgrade: composer require "anthropic-ai/sdk:^0.6"

use Anthropic\Messages\RawContentBlockDeltaEvent;
use Anthropic\Messages\TextDelta;

$stream = $client->messages->createStream(
    model: '{{OPUS_ID}}',
    maxTokens: 64000,
    messages: [
        ['role' => 'user', 'content' => 'Write a haiku'],
    ],
);

foreach ($stream as $event) {
    if ($event instanceof RawContentBlockDeltaEvent && $event->delta instanceof TextDelta) {
        echo $event->delta->text;
    }
}

Tool Use (Manual Loop)

Tools are passed as arrays. The SDK uses camelCase keys (inputSchema, toolUseID, stopReason) and auto-maps to the API's snake_case on the wire — since v0.5.0. See shared tool use concepts for the loop pattern.

use Anthropic\Messages\ToolUseBlock;

$tools = [
    [
        'name' => 'get_weather',
        'description' => 'Get the current weather in a given location',
        'inputSchema' => [  // camelCase, not input_schema
            'type' => 'object',
            'properties' => [
                'location' => ['type' => 'string', 'description' => 'City and state'],
            ],
            'required' => ['location'],
        ],
    ],
];

$messages = [['role' => 'user', 'content' => 'What is the weather in SF?']];

$response = $client->messages->create(
    model: '{{OPUS_ID}}',
    maxTokens: 16000,
    tools: $tools,
    messages: $messages,
);

while ($response->stopReason === 'tool_use') {  // camelCase property
    $toolResults = [];
    foreach ($response->content as $block) {
        if ($block instanceof ToolUseBlock) {
            // $block->name  : string               — tool name to dispatch on
            // $block->input : array<string,mixed>  — parsed JSON input
            // $block->id    : string               — pass back as toolUseID
            $result = executeYourTool($block->name, $block->input);
            $toolResults[] = [
                'type' => 'tool_result',
                'toolUseID' => $block->id,  // camelCase, not tool_use_id
                'content' => $result,
            ];
        }
    }

    // Append assistant turn + user turn with tool results
    $messages[] = ['role' => 'assistant', 'content' => $response->content];
    $messages[] = ['role' => 'user', 'content' => $toolResults];

    $response = $client->messages->create(
        model: '{{OPUS_ID}}',
        maxTokens: 16000,
        tools: $tools,
        messages: $messages,
    );
}

// Final text response
foreach ($response->content as $block) {
    if ($block->type === 'text') {
        echo $block->text;
    }
}

$block->type === 'tool_use' also works; instanceof ToolUseBlock narrows for PHPStan.

Extended Thinking

Adaptive thinking is the recommended mode for Claude 4.6+ models. Claude decides dynamically when and how much to think.

use Anthropic\Messages\ThinkingBlock;

$message = $client->messages->create(
    model: '{{OPUS_ID}}',
    maxTokens: 16000,
    thinking: ['type' => 'adaptive'],
    messages: [
        ['role' => 'user', 'content' => 'Solve: 27 * 453'],
    ],
);

// ThinkingBlock(s) precede TextBlock in content
foreach ($message->content as $block) {
    if ($block instanceof ThinkingBlock) {
        echo "Thinking:\n{$block->thinking}\n\n";
        // $block->signature is an opaque string — preserve verbatim if
        // passing thinking blocks back in multi-turn conversations
    } elseif ($block->type === 'text') {
        echo "Answer: {$block->text}\n";
    }
}

Deprecated: ['type' => 'enabled', 'budgetTokens' => N] (fixed-budget extended thinking) still works on Claude 4.6 but is deprecated. Use adaptive thinking above.

$block->type === 'thinking' also works for the check; instanceof narrows for PHPStan.

Beta Features & Server-Side Tools

betas: is NOT a param on $client->messages->create() — it only exists on the beta namespace. Use it for features that need an explicit opt-in header:

use Anthropic\Beta\Messages\BetaRequestMCPServerURLDefinition;

$response = $client->beta->messages->create(
    model: '{{OPUS_ID}}',
    maxTokens: 16000,
    mcpServers: [
        BetaRequestMCPServerURLDefinition::with(
            name: 'my-server',
            url: 'https://example.com/mcp',
        ),
    ],
    betas: ['mcp-client-2025-11-20'],  // only valid on ->beta->messages
    messages: [['role' => 'user', 'content' => 'Use the MCP tools']],
);

Server-side tools (bash, web_search, text_editor, code_execution) are GA and work on both paths — Anthropic\Messages\ToolBash20250124 / WebSearchTool20260209 / ToolTextEditor20250728 / CodeExecutionTool20260120 for non-beta, Anthropic\Beta\Messages\BetaToolBash20250124 / BetaWebSearchTool20260209 / BetaToolTextEditor20250728 / BetaCodeExecutionTool20260120 for beta. No betas: header needed for these.

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