Add _meta field for Tool

Author: kaipiyann

src/Capability/Attribute/McpTool.php

@@ -28,6 +28,7 @@ public function __construct(
         public ?string $name = null,
         public ?string $description = null,
         public ?ToolAnnotations $annotations = null,
+        public ?array $_meta = null,
     ) {
     }
 }

src/Capability/Discovery/Discoverer.php

@@ -222,7 +222,8 @@ private function processMethod(\ReflectionMethod $method, array &$discoveredCoun
                     $name = $instance->name ?? ('__invoke' === $methodName ? $classShortName : $methodName);
                     $description = $instance->description ?? $this->docBlockParser->getSummary($docBlock) ?? null;
                     $inputSchema = $this->schemaGenerator->generate($method);
-                    $tool = new Tool($name, $inputSchema, $description, $instance->annotations);
+                    $_meta = $instance->_meta ?? null;
+                    $tool = new Tool($name, $inputSchema, $description, $instance->annotations, $_meta);
                     $tools[$name] = new ToolReference($tool, [$className, $methodName], false);
                     ++$discoveredCount['tools'];
                     break;

src/Capability/Registry/Loader/ArrayLoader.php

@@ -102,7 +102,7 @@ public function load(ReferenceRegistryInterface $registry): void
 
                 $inputSchema = $data['inputSchema'] ?? $schemaGenerator->generate($reflection);
 
-                $tool = new Tool($name, $inputSchema, $description, $data['annotations']);
+                $tool = new Tool($name, $inputSchema, $description, $data['annotations'], $data['_meta'] ?? null);
                 $registry->registerTool($tool, $data['handler'], true);
 
                 $handlerDesc = $this->getHandlerDescription($data['handler']);

src/Schema/Tool.php

@@ -47,6 +47,7 @@ public function __construct(
         public readonly array $inputSchema,
         public readonly ?string $description,
         public readonly ?ToolAnnotations $annotations,
+        public readonly ?array $_meta = null,
     ) {
         if (!isset($inputSchema['type']) || 'object' !== $inputSchema['type']) {
             throw new InvalidArgumentException('Tool inputSchema must be a JSON Schema of type "object".');
@@ -75,7 +76,8 @@ public static function fromArray(array $data): self
             $data['name'],
             $data['inputSchema'],
             isset($data['description']) && \is_string($data['description']) ? $data['description'] : null,
-            isset($data['annotations']) && \is_array($data['annotations']) ? ToolAnnotations::fromArray($data['annotations']) : null
+            isset($data['annotations']) && \is_array($data['annotations']) ? ToolAnnotations::fromArray($data['annotations']) : null,
+            isset($data['_meta']) && \is_array($data['_meta']) ? $data['_meta'] : null
         );
     }
 
@@ -99,6 +101,9 @@ public function jsonSerialize(): array
         if (null !== $this->annotations) {
             $data['annotations'] = $this->annotations;
         }
+        if (null !== $this->_meta) {
+            $data['_meta'] = $this->_meta;
+        }
 
         return $data;
     }