diff --git a/router/src/lib.rs b/router/src/lib.rs
index 6f3a130b..560b8f74 100644
--- a/router/src/lib.rs
+++ b/router/src/lib.rs
@@ -107,7 +107,7 @@ pub(crate) struct GenerateParameters {
     #[schema(default = "false", example = true)]
     pub do_sample: bool,
     #[serde(default = "default_max_new_tokens")]
-    #[schema(exclusive_minimum = 0, exclusive_maximum = 512, default = "null")]
+    #[schema(nullable = true, default = "null", example = "20")]
     pub max_new_tokens: Option<u32>,
     #[serde(default)]
     #[schema(nullable = true, default = "null", example = false)]