​
Overview

ToolUse class automates the process of using tools by LLM, i.e.:

  • calling LLM with provided context (message sequence),
  • extracting tool calls requested by LLM from the response,
  • calling the requested tool and storing its results,
  • constructing message sequence with the result of call,
  • sending updated message sequence back to LLM.

This cycle is repeated until one of the exit criteria is met:

  • LLM no longer requests any tool calls,
  • specified maximum number of iterations is reached,
  • specified token usage limit is reached
  • there are any errors during the process (e.g. LLM requested a tool that is not available).

ToolUse class provides 3 ways to iterate through the process:

  • manual control - code is responsible for checking hasNextStep() and calling nextStep() in a loop,
  • using iterator - code uses foreach loop to iterate through the steps (internally it checks hasNextStep() and calls nextStep()),
  • just get final step - you only get the final step, iteration process is done internally.

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Example

This example demonstrates 3 ways to use ToolUse class to allow LLM call functions if needed to answer simple math question. We provide 2 functions (add_numbers and subtract_numbers) as tools available to LLM and specify the task in plain language. The LLM is expected to call the functions in the correct order to get the final result.

<?php

use Cognesy\Instructor\Extras\ToolUse\Tools\FunctionTool;
use Cognesy\Instructor\Extras\ToolUse\ToolUse;

$loader = require 'vendor/autoload.php';
$loader->add('Cognesy\\Instructor\\', __DIR__ . '../../src/');

//Debug::enable();

function add_numbers(int $a, int $b) : int {
    return $a + $b;
}

function subtract_numbers(int $a, int $b) : int {
    return $a - $b;
}

//
// PATTERN #1 - manual control
//
echo "\nPATTERN #1 - manual control\n";
$toolUse = (new ToolUse)
    ->withMessages('Add 2455 and 3558 then subtract 4344 from the result.')
    ->withTools([
        FunctionTool::fromCallable(add_numbers(...)),
        FunctionTool::fromCallable(subtract_numbers(...)),
    ]);

// iterate until no more steps
while ($toolUse->hasNextStep()) {
    $step = $toolUse->nextStep();
    print("STEP - tokens used: " . $step->usage()->total() . "\n");
}

// print final response
$result = $step->response();
print("RESULT: " . $result . "\n");


//
// PATTERN #2 - using iterator
//
echo "\nPATTERN #2 - using iterator\n";
$toolUse = (new ToolUse)
    ->withMessages('Add 2455 and 3558 then subtract 4344 from the result.')
    ->withTools([
        FunctionTool::fromCallable(add_numbers(...)),
        FunctionTool::fromCallable(subtract_numbers(...)),
    ]);

// iterate until no more steps
foreach ($toolUse->iterator() as $step) {
    print("STEP - tokens used: " . $step->usage()->total() . "\n");
}

// print final response
$result = $toolUse->context()->currentStep()->response();
print("RESULT: " . $result . "\n");



//
// PATTERN #3 - just get final step (fast forward to it)
//
echo "\nPATTERN #3 - get only final result\n";
$toolUse = (new ToolUse)
    ->withMessages('Add 2455 and 3558 then subtract 4344 from the result.')
    ->withTools([
        FunctionTool::fromCallable(add_numbers(...)),
        FunctionTool::fromCallable(subtract_numbers(...)),
    ]);

// print final response
$result = $toolUse->finalStep()->response();
print("RESULT: " . $result . "\n");
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