fix: re-enable filtering of tools (#223)

Author: chr-hertel

README.md

@@ -245,6 +245,15 @@ $toolProcessor = new ChainProcessor($toolBox);
 $chain = new Chain($platform, $llm, inputProcessor: [$toolProcessor], outputProcessor: [$toolProcessor]);
 ```
 
+#### Tool Filtering
+
+To limit the tools provided to the LLM in a specific chain call to a subset of the configured tools, you can use the
+`tools` option with a list of tool names:
+
+```php
+$this->chain->call($messages, ['tools' => ['tavily_search']]);
+```
+
 #### Tool Result Interception
 
 To react to the result of a tool, you can implement an EventListener or EventSubscriber, that listens to the

src/Chain/ToolBox/ChainProcessor.php

@@ -43,6 +43,10 @@ public function processInput(Input $input): void
         }
 
         $options = $input->getOptions();
+        if (isset($options['tools'])) {
+            $toolMap = array_filter($toolMap, fn (string $tool) => in_array($tool, $options['tools'], true), ARRAY_FILTER_USE_KEY);
+        }
+
         $options['tools'] = $toolMap;
         $input->setOptions($options);
     }

tests/Chain/ToolBox/ChainProcessorTest.php

@@ -55,6 +55,23 @@ public function processInputWithRegisteredToolsWillResultInOptionChange(): void
         self::assertSame(['tools' => ['tool1' => 'tool1', 'tool2' => 'tool2']], $input->getOptions());
     }
 
+    #[Test]
+    public function processInputWithRegisteredToolsButToolOverride(): void
+    {
+        $toolBox = $this->createStub(ToolBoxInterface::class);
+        $toolBox->method('getMap')->willReturn(['tool1' => 'tool1-metadata', 'tool2' => 'tool2-metadata']);
+
+        $llm = $this->createMock(LanguageModel::class);
+        $llm->method('supportsToolCalling')->willReturn(true);
+
+        $chainProcessor = new ChainProcessor($toolBox);
+        $input = new Input($llm, new MessageBag(), ['tools' => ['tool2']]);
+
+        $chainProcessor->processInput($input);
+
+        self::assertSame(['tools' => ['tool2' => 'tool2-metadata']], $input->getOptions());
+    }
+
     #[Test]
     public function processInputWithUnsupportedToolCallingWillThrowException(): void
     {