Computer Use is a groundbreaking capability allowing Claude to manipulate a desktop OS (Linux/Windows) via the mouse and keyboard. Because it is experimental, it requires the anthropic-beta: computer-use-2024-10-22 header. The model doesn't 'control' the computer directly—it takes a screenshot, calculates the X/Y coordinates of an element, and returns a 'tool call' commanding your sandbox to perform the action.
If your Docker sandbox runs at 1024x768 but your API request scales the screenshot down to 800x600 for performance, you MUST correctly define the display_width_px and display_height_px. If these bounds are misaligned, Claude's internal math will 'miss' the target, clicking on empty space. Alignment is the #1 cause of failure in Computer Use implementations.