Basic Agent

The simplest agent uses AgentLoop to send a message and get a response.

Hello World

use Cognesy\Agents\Core\AgentLoop;
use Cognesy\Agents\Core\Data\AgentState;

$loop = AgentLoop::default();
$state = AgentState::empty()->withUserMessage('What is 2+2?');
$result = $loop->execute($state);

echo $result->finalResponse()->toString();
// "2 + 2 equals 4."

What Happens

1. AgentLoop::execute() starts the loop
2. The driver (ToolCallingDriver) sends messages to the LLM
3. LLM responds with text (no tool calls)
4. The loop detects no tool calls and stops
5. Final response is available via $result->finalResponse()

Customizing the Loop

Use with() to swap components on the default loop:

use Cognesy\Agents\Core\Collections\Tools;
use Cognesy\Agents\Drivers\ReAct\ReActDriver;

// Add tools
$loop = AgentLoop::default()->withTool($myTool);

// Swap driver
$loop = AgentLoop::default()->withDriver(new ReActDriver(model: 'gpt-4o'));

System Prompt

$state = AgentState::empty()
    ->withSystemPrompt('You are a helpful assistant.')
    ->withUserMessage('Hello!');