fix: remove scaling injection from MCP server — device handles defaults

Passthrough layers (MCP servers) should not inject scaling defaults.
Each device applies its own defaults based on screen ratio. MCP servers
only expose the schema so AI assistants know the params exist.

Author: shimondoodkin

mcp-server/src/mcp.ts

@@ -11,32 +11,12 @@ const deviceConnections = new Map<string, DeviceConnection>();
 // Common device_id parameter added to every phone tool
 const deviceIdParam = z.number().int().describe('Device ID number. Use list_devices to see available devices.');
 
-// Default scaling resolution (landscape)
-const DEFAULT_SCALE_WIDTH = 1456;
-const DEFAULT_SCALE_HEIGHT = 819;
-
-// Optional coordinate scaling params — pass the same max_width/max_height used for screenshot
+// Optional coordinate scaling params — device applies defaults based on its own screen ratio
 const scalingParams = {
-  max_width: z.number().int().optional().describe(`Screenshot width for coordinate auto-scaling (default: ${DEFAULT_SCALE_WIDTH}, 0 to disable)`),
-  max_height: z.number().int().optional().describe(`Screenshot height for coordinate auto-scaling (default: ${DEFAULT_SCALE_HEIGHT}, 0 to disable)`),
+  max_width: z.number().int().optional().describe('Screenshot width for coordinate auto-scaling (device applies default if omitted, 0 to disable)'),
+  max_height: z.number().int().optional().describe('Screenshot height for coordinate auto-scaling (device applies default if omitted, 0 to disable)'),
 };
 
-// Tools that need default scaling injected
-const SCALING_TOOLS = new Set([
-  'screenshot', 'screenshot_window', 'click', 'long_click', 'double_click',
-  'right_click', 'middle_click', 'mouse_move', 'mouse_scroll', 'drag', 'scroll',
-  'ui_tree', 'list_windows', 'get_screen_size', 'active_window', 'camera',
-]);
-
-/** Inject default max_width/max_height if not specified and tool needs scaling. */
-function injectScalingDefaults(toolName: string, params: Record<string, unknown>): Record<string, unknown> {
-  if (!SCALING_TOOLS.has(toolName)) return params;
-  const p = { ...params };
-  if (p.max_width === undefined) p.max_width = DEFAULT_SCALE_WIDTH;
-  if (p.max_height === undefined) p.max_height = DEFAULT_SCALE_HEIGHT;
-  return p;
-}
-
 // MCP tools for phone control — descriptions match web/ exactly
 const phoneTools = [
   {
@@ -521,8 +501,7 @@ export function createMcpHandler(
 
             const p = await getPhone(deviceId);
             const { device_id: _, ...phoneParams } = params;
-            const scaledParams = injectScalingDefaults(tool.name, phoneParams);
-            const result = await tool.handler(p, scaledParams);
+            const result = await tool.handler(p, phoneParams);
             return {
               content: [{ type: 'text' as const, text: JSON.stringify(result, null, 2) }],
             };