Improve code comments and help text clarity

- Add detailed comment explaining IsBoolFlag behavior
- Update help text with specific usage examples
- Address code review feedback

Co-authored-by: keac <[email protected]>

Author: Copilot

common/flag.go

@@ -18,8 +18,10 @@ func (m *mcpFlag) String() string {
 }
 
 func (m *mcpFlag) Set(s string) error {
-	// When IsBoolFlag returns true and flag is used without value,
-	// Go sets it to "true". We treat "true" as "use config default"
+	// When IsBoolFlag returns true and the flag is used without a value (e.g., --mcp alone),
+	// Go's flag parser calls Set with "true" as the value.
+	// We treat this special case as "use config default" by setting value to empty string.
+	// For any other value (e.g., --mcp=:8080), we use that value directly.
 	if s == "true" {
 		m.value = ""  // Empty means use config default
 	} else {
@@ -84,7 +86,7 @@ func Flag(Info *ENOptions) {
 
 	// MCP flag with optional value support
 	mcpFlagVar := &mcpFlag{}
-	flag.Var(mcpFlagVar, "mcp", "MCP模式运行，可指定监听地址，如 :8080 或 http://localhost:8080，不指定则使用配置文件默认值")
+	flag.Var(mcpFlagVar, "mcp", "MCP模式运行。用法: --mcp (使用配置文件默认值), --mcp=:8080 (自定义端口), --mcp=http://localhost:8080 (完整地址)")
 
 	flag.BoolVar(&Info.ISKeyPid, "is-pid", false, "批量查询文件是否为公司PID")
 	flag.IntVar(&Info.DelayTime, "delay", 0, "每个请求延迟（S）-1为随机延迟1-5S")