fix: allow setting request description and still gen schema

huma.go

@@ -572,30 +572,30 @@ func Register[I, O any](api API, op Operation, handler func(context.Context, *I)
 		hasInputBody = true
 		inputBodyIndex = f.Index
 		if op.RequestBody == nil {
-			required := f.Type.Kind() != reflect.Ptr && f.Type.Kind() != reflect.Interface
-			if f.Tag.Get("required") == "true" {
-				required = true
-			}
+			op.RequestBody = &RequestBody{}
+		}
 
-			contentType := "application/json"
-			if c := f.Tag.Get("contentType"); c != "" {
-				contentType = c
-			}
-			hint := getHint(inputType, f.Name, op.OperationID+"Request")
-			if nameHint := f.Tag.Get("nameHint"); nameHint != "" {
-				hint = nameHint
-			}
-			s := SchemaFromField(registry, f, hint)
+		required := f.Type.Kind() != reflect.Ptr && f.Type.Kind() != reflect.Interface
+		if f.Tag.Get("required") == "true" {
+			required = true
+		}
 
-			op.RequestBody = &RequestBody{
-				Required: required,
-				Content: map[string]*MediaType{
-					contentType: {
-						Schema: s,
-					},
-				},
-			}
+		contentType := "application/json"
+		if c := f.Tag.Get("contentType"); c != "" {
+			contentType = c
 		}
+		hint := getHint(inputType, f.Name, op.OperationID+"Request")
+		if nameHint := f.Tag.Get("nameHint"); nameHint != "" {
+			hint = nameHint
+		}
+		s := SchemaFromField(registry, f, hint)
+
+		op.RequestBody.Required = required
+
+		if op.RequestBody.Content == nil {
+			op.RequestBody.Content = map[string]*MediaType{}
+		}
+		op.RequestBody.Content[contentType] = &MediaType{Schema: s}
 
 		if op.BodyReadTimeout == 0 {
 			// 5 second default
@@ -615,10 +615,13 @@ func Register[I, O any](api API, op Operation, handler func(context.Context, *I)
 		if op.RequestBody == nil {
 			op.RequestBody = &RequestBody{
 				Required: true,
-				Content:  map[string]*MediaType{},
 			}
 		}
 
+		if op.RequestBody.Content == nil {
+			op.RequestBody.Content = map[string]*MediaType{}
+		}
+
 		contentType := "application/octet-stream"
 
 		if f.Type.String() == "multipart.Form" {

huma_test.go

@@ -544,6 +544,42 @@ func TestFeatures(t *testing.T) {
 			// Headers: map[string]string{"Content-Type": "application/json"},
 			Body: `{"name":"foo"}`,
 		},
+		{
+			Name: "request-body-description",
+			Register: func(t *testing.T, api huma.API) {
+				huma.Register(api, huma.Operation{
+					Method: http.MethodPut,
+					Path:   "/body",
+					RequestBody: &huma.RequestBody{
+						Description: "A description",
+					},
+				}, func(ctx context.Context, input *struct {
+					Body struct {
+						Name string `json:"name"`
+					}
+				}) (*struct{}, error) {
+					assert.Equal(t, "foo", input.Body.Name)
+					return nil, nil
+				})
+				// Note: the description should be set, but *also* the generated
+				// schema should be present since we didn't set it up ourselves.
+				b, _ := api.OpenAPI().Paths["/body"].Put.RequestBody.MarshalJSON()
+				assert.JSONEq(t, `{
+					"description": "A description",
+					"required": true,
+					"content": {
+						"application/json": {
+							"schema": {
+								"$ref": "#/components/schemas/Request"
+							}
+						}
+					}
+				}`, string(b))
+			},
+			Method: http.MethodPut,
+			URL:    "/body",
+			Body:   `{"name":"foo"}`,
+		},
 		{
 			Name: "request-body-nested-struct-readOnly",
 			Register: func(t *testing.T, api huma.API) {