diff --git a/cmd/api/cmd_sdk.go b/cmd/api/cmd_sdk.go
index da85d75..1ea0949 100644
--- a/cmd/api/cmd_sdk.go
+++ b/cmd/api/cmd_sdk.go
@@ -108,7 +108,7 @@ func addSDKCommand(parent *cli.Command) {
 
 	cli.StringFlag(cmd, &lang, "lang", "l", "", "Target language(s), comma-separated (e.g. go,python,typescript-fetch)")
 	cli.StringFlag(cmd, &output, "output", "o", "./sdk", "Output directory for generated SDKs")
-	cli.StringFlag(cmd, &specFile, "spec", "s", "", "Path to existing OpenAPI spec (generates from MCP tools if not provided)")
+	cli.StringFlag(cmd, &specFile, "spec", "s", "", "Path to an existing OpenAPI spec (generates a temporary spec from registered route groups and the built-in tool bridge if not provided)")
 	cli.StringFlag(cmd, &packageName, "package", "p", "lethean", "Package name for generated SDK")
 	cli.StringFlag(cmd, &title, "title", "t", defaultSDKTitle, "API title in generated spec")
 	cli.StringFlag(cmd, &description, "description", "d", defaultSDKDescription, "API description in generated spec")
diff --git a/export.go b/export.go
index d5d68d8..3095a6c 100644
--- a/export.go
+++ b/export.go
@@ -9,6 +9,7 @@ import (
 	"iter"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"gopkg.in/yaml.v3"
 
@@ -47,7 +48,7 @@ func ExportSpecIter(w io.Writer, format string, builder *SpecBuilder, groups ite
 }
 
 func writeSpec(w io.Writer, format string, data []byte, op string) error {
-	switch format {
+	switch strings.ToLower(strings.TrimSpace(format)) {
 	case "json":
 		_, err := w.Write(data)
 		return err
diff --git a/export_test.go b/export_test.go
index 1288381..926b5c3 100644
--- a/export_test.go
+++ b/export_test.go
@@ -66,6 +66,24 @@ func TestExportSpec_Good_YAML(t *testing.T) {
 	}
 }
 
+func TestExportSpec_Good_NormalisesFormatInput(t *testing.T) {
+	builder := &api.SpecBuilder{Title: "Test", Description: "Test API", Version: "1.0.0"}
+
+	var buf bytes.Buffer
+	if err := api.ExportSpec(&buf, " YAML ", builder, nil); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	var spec map[string]any
+	if err := yaml.Unmarshal(buf.Bytes(), &spec); err != nil {
+		t.Fatalf("output is not valid YAML: %v", err)
+	}
+
+	if spec["openapi"] != "3.1.0" {
+		t.Fatalf("expected openapi=3.1.0, got %v", spec["openapi"])
+	}
+}
+
 func TestExportSpec_Bad_InvalidFormat(t *testing.T) {
 	builder := &api.SpecBuilder{Title: "Test", Description: "Test API", Version: "1.0.0"}