diff --git a/cmd/generate.go b/cmd/generate.go
index 8e7f69a..c94bbd7 100644
--- a/cmd/generate.go
+++ b/cmd/generate.go
@@ -13,6 +13,8 @@ import (
 	"github.com/spf13/cobra"
 )
 
+var generateArgMax = 1
+
 func init() {
 	rootCmd.AddCommand(generateCmd)
 }
@@ -117,6 +119,29 @@ func newGenerateCmd() *cobra.Command {
 
 			return err
 		},
+		PreRunE: func(cmd *cobra.Command, args []string) error {
+			if len(args) > generateArgMax {
+				return errTooManyArguments
+			}
+
+			// validate flags
+			_, err := cmd.Flags().GetString("output")
+			if err != nil {
+				return err
+			}
+
+			formatString, err := cmd.Flags().GetString("format")
+			if err != nil {
+				return errors.Join(errMissingFormat, err)
+			}
+
+			_, err = ParseFmtString(formatString)
+			if err != nil && formatString != "" {
+				return errors.Join(errInvalidFormat, err)
+			}
+
+			return nil
+		},
 	}
 
 	res.Version = VERSION
diff --git a/cmd/generate_test.go b/cmd/generate_test.go
new file mode 100644
index 0000000..3531466
--- /dev/null
+++ b/cmd/generate_test.go
@@ -0,0 +1,43 @@
+//go:build unit
+
+package cmd
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestRunEGenerate(t *testing.T) {
+	type runTestGen struct {
+		flags       []string
+		arguments   []string
+		expectError error
+	}
+
+	var testGenArgs = []runTestGen{
+		{
+			flags:       []string{},
+			arguments:   []string{"too", "many", "args"},
+			expectError: errTooManyArguments,
+		},
+		{
+			flags:       []string{"--format", "bad_fmt"},
+			arguments:   []string{},
+			expectError: errInvalidFormat,
+		},
+		{
+			flags:       []string{"-F", "bad_fmt"},
+			arguments:   []string{},
+			expectError: errInvalidFormat,
+		},
+	}
+	cmd := newGenerateCmd()
+
+	for i, test := range testGenArgs {
+		cmd.ParseFlags(test.flags)
+		err := cmd.PreRunE(cmd, test.arguments)
+		if !errors.Is(err, test.expectError) {
+			t.Fatalf("case: %d, expectError: %v does not match err: %v", i, test.expectError, err)
+		}
+	}
+}