fix(discovery): fix empty schema in tool discovery

Author: EdouardCourty

src/Service/ResponseFactory.php

@@ -9,6 +9,7 @@
 use Ecourty\McpServerBundle\HttpFoundation\JsonRpcResponse;
 use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\Serializer\Normalizer\AbstractObjectNormalizer;
+use Symfony\Component\Serializer\Serializer;
 use Symfony\Component\Serializer\SerializerInterface;
 
 /**
@@ -46,6 +47,8 @@ private function createResponse(JsonRpcResponse $response): JsonResponse
     {
         $json = $this->serializer->serialize($response, 'json', [
             AbstractObjectNormalizer::SKIP_NULL_VALUES => true,
+            AbstractObjectNormalizer::PRESERVE_EMPTY_OBJECTS => true,
+            Serializer::EMPTY_ARRAY_AS_OBJECT => true,
         ]);
 
         return JsonResponse::fromJsonString($json, JsonResponse::HTTP_OK);

tests/Controller/EntrypointControllerTest.php

@@ -152,7 +152,7 @@ public function testToolList(): void
         ], $tools[0]['annotations']);
 
         $this->assertArrayHasKey('inputSchema', $tools[1]);
-        $this->assertSame([], $tools[1]['inputSchema']);
+        $this->assertEmpty($tools[1]['inputSchema']);
 
         $this->assertArrayHasKey('inputSchema', $tools[2]);
         $this->assertSame([