diff --git a/lambda-runtime/src/runtime.rs b/lambda-runtime/src/runtime.rs
index caac0983..d8726a5e 100644
--- a/lambda-runtime/src/runtime.rs
+++ b/lambda-runtime/src/runtime.rs
@@ -45,6 +45,9 @@ where
 }
 
 #[macro_export]
+/// Starts an event listener which will parse incoming events into the even type requested by
+/// `handler` and will invoke `handler` on each incoming event. Can optionally be passed a Tokio
+/// `runtime` to build the listener on. If none is provided, it creates its own.
 macro_rules! lambda {
     ($handler:ident) => {
         $crate::start($handler, None)