diff --git a/codex-rs/mcp-server/src/wire_format.rs b/codex-rs/mcp-server/src/wire_format.rs
index f2702a1d..4a2346cb 100644
--- a/codex-rs/mcp-server/src/wire_format.rs
+++ b/codex-rs/mcp-server/src/wire_format.rs
@@ -144,6 +144,7 @@ pub struct RemoveConversationListenerParams {
 
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
 #[serde(rename_all = "camelCase")]
+#[serde(tag = "type", content = "data")]
 pub enum InputItem {
     Text {
         text: String,