From b482cfc4bb072c4ea3ad146f881c62b08aacfddd Mon Sep 17 00:00:00 2001
From: Dale Seo <5466341+DaleSeo@users.noreply.github.com>
Date: Mon, 8 Sep 2025 02:40:02 -0400
Subject: [PATCH] fix: generate simple {} schema for tools with no parameters
 (#425)

---
 crates/rmcp-macros/src/tool.rs        | 4 ++--
 crates/rmcp/tests/test_tool_macros.rs | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/crates/rmcp-macros/src/tool.rs b/crates/rmcp-macros/src/tool.rs
index a9c6e0d..f50ba93 100644
--- a/crates/rmcp-macros/src/tool.rs
+++ b/crates/rmcp-macros/src/tool.rs
@@ -186,9 +186,9 @@ pub fn tool(attr: TokenStream, input: TokenStream) -> syn::Result<TokenStream> {
                 rmcp::handler::server::common::cached_schema_for_type::<#params_ty>()
             })?
         } else {
-            // if not found, use the default EmptyObject schema
+            // if not found, use a simple empty JSON object
             syn::parse2::<Expr>(quote! {
-                rmcp::handler::server::common::cached_schema_for_type::<rmcp::model::EmptyObject>()
+                std::sync::Arc::new(serde_json::Map::new())
             })?
         }
     };
diff --git a/crates/rmcp/tests/test_tool_macros.rs b/crates/rmcp/tests/test_tool_macros.rs
index e30d31c..8825f12 100644
--- a/crates/rmcp/tests/test_tool_macros.rs
+++ b/crates/rmcp/tests/test_tool_macros.rs
@@ -110,7 +110,7 @@ async fn test_tool_macros() {
 async fn test_tool_macros_with_empty_param() {
     let _attr = Server::empty_param_tool_attr();
     println!("{_attr:?}");
-    assert_eq!(_attr.input_schema.get("type").unwrap(), "object");
+    assert!(_attr.input_schema.get("type").is_none());
     assert!(_attr.input_schema.get("properties").is_none());
 }