diff --git a/codex-rs/app-server-protocol/src/protocol/v2.rs b/codex-rs/app-server-protocol/src/protocol/v2.rs
index 22d53c3de..f650d4d1f 100644
--- a/codex-rs/app-server-protocol/src/protocol/v2.rs
+++ b/codex-rs/app-server-protocol/src/protocol/v2.rs
@@ -1141,6 +1141,9 @@ pub enum ThreadItem {
         arguments: JsonValue,
         result: Option<McpToolCallResult>,
         error: Option<McpToolCallError>,
+        /// The duration of the MCP tool call in milliseconds.
+        #[ts(type = "number | null")]
+        duration_ms: Option<i64>,
     },
     #[serde(rename_all = "camelCase")]
     #[ts(rename_all = "camelCase")]
diff --git a/codex-rs/app-server/src/bespoke_event_handling.rs b/codex-rs/app-server/src/bespoke_event_handling.rs
index 8e39580fa..547daf08b 100644
--- a/codex-rs/app-server/src/bespoke_event_handling.rs
+++ b/codex-rs/app-server/src/bespoke_event_handling.rs
@@ -1178,6 +1178,7 @@ async fn construct_mcp_tool_call_notification(
         arguments: begin_event.invocation.arguments.unwrap_or(JsonValue::Null),
         result: None,
         error: None,
+        duration_ms: None,
     };
     ItemStartedNotification {
         thread_id,
@@ -1197,6 +1198,7 @@ async fn construct_mcp_tool_call_end_notification(
     } else {
         McpToolCallStatus::Failed
     };
+    let duration_ms = i64::try_from(end_event.duration.as_millis()).ok();
 
     let (result, error) = match &end_event.result {
         Ok(value) => (
@@ -1222,6 +1224,7 @@ async fn construct_mcp_tool_call_end_notification(
         arguments: end_event.invocation.arguments.unwrap_or(JsonValue::Null),
         result,
         error,
+        duration_ms,
     };
     ItemCompletedNotification {
         thread_id,
@@ -1598,6 +1601,7 @@ mod tests {
                 arguments: serde_json::json!({"server": ""}),
                 result: None,
                 error: None,
+                duration_ms: None,
             },
         };
 
@@ -1751,6 +1755,7 @@ mod tests {
                 arguments: JsonValue::Null,
                 result: None,
                 error: None,
+                duration_ms: None,
             },
         };
 
@@ -1804,6 +1809,7 @@ mod tests {
                     structured_content: None,
                 }),
                 error: None,
+                duration_ms: Some(0),
             },
         };
 
@@ -1845,6 +1851,7 @@ mod tests {
                 error: Some(McpToolCallError {
                     message: "boom".to_string(),
                 }),
+                duration_ms: Some(1),
             },
         };