diff --git a/codex-rs/protocol/src/protocol.rs b/codex-rs/protocol/src/protocol.rs
index 48f6404368..32b49f9f82 100644
--- a/codex-rs/protocol/src/protocol.rs
+++ b/codex-rs/protocol/src/protocol.rs
@@ -579,7 +579,7 @@ pub struct TokenUsage {
 pub struct TokenUsageInfo {
     /// The total token usage for the session. accumulated from all turns.
     pub total_token_usage: TokenUsage,
-    /// The token usage for the last turn. Received from the API.
+    /// The token usage for the last turn. Received from the API. It's total tokens is the whole window size.
     pub last_token_usage: TokenUsage,
     #[ts(type = "number | null")]
     pub model_context_window: Option<i64>,