fix(model): skip extensions field in json schema generation

The `Extensions` type was incorrectly included in JSON schema
generation, which could lead to confusing API documentation. This commit
adds `#[schemars(skip)]` attribute to all `extensions` fields in request
and notification structs, and removes the manual `JsonSchema`
implementation for the `Extensions` type since it's an internal
implementation detail that shouldn't be exposed in the schema.

Author: shorwood

crates/rmcp/src/model.rs

@@ -243,6 +243,7 @@ pub struct Request<M = String, P = JsonObject> {
     /// extensions will carry anything possible in the context, including [`Meta`]
     ///
     /// this is similar with the Extensions in `http` crate
+    #[schemars(skip)]
     pub extensions: Extensions,
 }
 
@@ -264,6 +265,7 @@ pub struct RequestOptionalParam<M = String, P = JsonObject> {
     /// extensions will carry anything possible in the context, including [`Meta`]
     ///
     /// this is similar with the Extensions in `http` crate
+    #[schemars(skip)]
     pub extensions: Extensions,
 }
 
@@ -274,6 +276,7 @@ pub struct RequestNoParam<M = String> {
     /// extensions will carry anything possible in the context, including [`Meta`]
     ///
     /// this is similar with the Extensions in `http` crate
+    #[schemars(skip)]
     pub extensions: Extensions,
 }
 
@@ -293,6 +296,7 @@ pub struct Notification<M = String, P = JsonObject> {
     /// extensions will carry anything possible in the context, including [`Meta`]
     ///
     /// this is similar with the Extensions in `http` crate
+    #[schemars(skip)]
     pub extensions: Extensions,
 }
 
@@ -303,6 +307,7 @@ pub struct NotificationNoParam<M = String> {
     /// extensions will carry anything possible in the context, including [`Meta`]
     ///
     /// this is similar with the Extensions in `http` crate
+    #[schemars(skip)]
     pub extensions: Extensions,
 }
 

crates/rmcp/src/model/extension.rs

@@ -279,16 +279,6 @@ impl fmt::Debug for Extensions {
     }
 }
 
-impl schemars::JsonSchema for Extensions {
-    fn schema_name() -> String {
-        "Extensions".to_string()
-    }
-
-    fn json_schema(generator: &mut schemars::SchemaGenerator) -> schemars::schema::Schema {
-        generator.subschema_for::<serde_json::Value>()
-    }
-}
-
 trait AnyClone: Any {
     fn clone_box(&self) -> Box<dyn AnyClone + Send + Sync>;
     fn as_any(&self) -> &dyn Any;

crates/rmcp/tests/test_message_schema.rs

@@ -1,22 +1,40 @@
-#[cfg(feature = "schemars")]
 mod tests {
     use rmcp::model::{ClientJsonRpcMessage, ServerJsonRpcMessage};
-    use super::*;
     use schemars::schema_for;
 
     #[test]
     fn test_client_json_rpc_message_schema() {
         let schema = schema_for!(ClientJsonRpcMessage);
         let schema_str = serde_json::to_string_pretty(&schema).unwrap();
-        let expected = std::fs::read_to_string("tests/test_message_schema/client_json_rpc_message_schema.json").unwrap();
-        assert_eq!(schema_str, expected, "Schema generation for ClientJsonRpcMessage should match expected output");
+        let expected = std::fs::read_to_string(
+            "tests/test_message_schema/client_json_rpc_message_schema.json",
+        )
+        .unwrap();
+
+        // Parse both strings to JSON values for more robust comparison
+        let schema_json: serde_json::Value = serde_json::from_str(&schema_str).unwrap();
+        let expected_json: serde_json::Value = serde_json::from_str(&expected).unwrap();
+        assert_eq!(
+            schema_json, expected_json,
+            "Schema generation for ClientJsonRpcMessage should match expected output"
+        );
     }
 
     #[test]
     fn test_server_json_rpc_message_schema() {
         let schema = schema_for!(ServerJsonRpcMessage);
         let schema_str = serde_json::to_string_pretty(&schema).unwrap();
-        let expected = std::fs::read_to_string("tests/test_message_schema/server_json_rpc_message_schema.json").unwrap();
-        assert_eq!(schema_str, expected, "Schema generation for ServerJsonRpcMessage should match expected output");
+        let expected = std::fs::read_to_string(
+            "tests/test_message_schema/server_json_rpc_message_schema.json",
+        )
+        .unwrap();
+
+        // Parse both strings to JSON values for more robust comparison
+        let schema_json: serde_json::Value = serde_json::from_str(&schema_str).unwrap();
+        let expected_json: serde_json::Value = serde_json::from_str(&expected).unwrap();
+        assert_eq!(
+            schema_json, expected_json,
+            "Schema generation for ServerJsonRpcMessage should match expected output"
+        );
     }
 }