Added private -> protected for tools list in McpAsyncServer

Author: Scott Lewis

mcp-core/src/main/java/io/modelcontextprotocol/server/McpAsyncServer.java

@@ -103,7 +103,7 @@ public class McpAsyncServer {
 
 	private final String instructions;
 
-	private final CopyOnWriteArrayList<McpServerFeatures.AsyncToolSpecification> tools = new CopyOnWriteArrayList<>();
+	protected final CopyOnWriteArrayList<McpServerFeatures.AsyncToolSpecification> tools = new CopyOnWriteArrayList<>();
 
 	private final ConcurrentHashMap<String, McpServerFeatures.AsyncResourceSpecification> resources = new ConcurrentHashMap<>();