diff --git a/codex-rs/app-server-protocol/src/protocol/v2.rs b/codex-rs/app-server-protocol/src/protocol/v2.rs
index ac3df37bd08..1e28b1b086e 100644
--- a/codex-rs/app-server-protocol/src/protocol/v2.rs
+++ b/codex-rs/app-server-protocol/src/protocol/v2.rs
@@ -2593,7 +2593,7 @@ pub struct ToolRequestUserInputOption {
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]
-/// EXPERIMENTAL. Represents one request_user_input question and its optional options.
+/// EXPERIMENTAL. Represents one request_user_input question and its required options.
 pub struct ToolRequestUserInputQuestion {
     pub id: String,
     pub header: String,
diff --git a/codex-rs/app-server/tests/common/responses.rs b/codex-rs/app-server/tests/common/responses.rs
index 2a5b5d21597..e15319e02f9 100644
--- a/codex-rs/app-server/tests/common/responses.rs
+++ b/codex-rs/app-server/tests/common/responses.rs
@@ -67,7 +67,6 @@ pub fn create_request_user_input_sse_response(call_id: &str) -> anyhow::Result<S
             "id": "confirm_path",
             "header": "Confirm",
             "question": "Proceed with the plan?",
-            "isOther": false,
             "options": [{
                 "label": "Yes (Recommended)",
                 "description": "Continue the current plan."
diff --git a/codex-rs/core/src/tools/handlers/request_user_input.rs b/codex-rs/core/src/tools/handlers/request_user_input.rs
index 112dcae21ea..b78bb51181d 100644
--- a/codex-rs/core/src/tools/handlers/request_user_input.rs
+++ b/codex-rs/core/src/tools/handlers/request_user_input.rs
@@ -49,7 +49,19 @@ impl ToolHandler for RequestUserInputHandler {
             )));
         }
 
-        let args: RequestUserInputArgs = parse_arguments(&arguments)?;
+        let mut args: RequestUserInputArgs = parse_arguments(&arguments)?;
+        let missing_options = args
+            .questions
+            .iter()
+            .any(|question| question.options.as_ref().is_none_or(Vec::is_empty));
+        if missing_options {
+            return Err(FunctionCallError::RespondToModel(
+                "request_user_input requires non-empty options for every question".to_string(),
+            ));
+        }
+        for question in &mut args.questions {
+            question.is_other = true;
+        }
         let response = session
             .request_user_input(turn.as_ref(), call_id, args)
             .await
diff --git a/codex-rs/core/src/tools/spec.rs b/codex-rs/core/src/tools/spec.rs
index df65a94d8a7..bf3b7b4b256 100644
--- a/codex-rs/core/src/tools/spec.rs
+++ b/codex-rs/core/src/tools/spec.rs
@@ -571,7 +571,7 @@ fn create_request_user_input_tool() -> ToolSpec {
 
     let options_schema = JsonSchema::Array {
         description: Some(
-            "Optional 2-3 mutually exclusive choices. Put the recommended option first and suffix its label with \"(Recommended)\". Do not include an \"Other\" option in this list; use isOther on the question to request a free form choice. If the question is free form in nature, please do not have any option."
+            "Provide 2-3 mutually exclusive choices. Put the recommended option first and suffix its label with \"(Recommended)\". Do not include an \"Other\" option in this list; the client will add a free-form \"Other\" option automatically."
                 .to_string(),
         ),
         items: Box::new(JsonSchema::Object {
@@ -602,15 +602,6 @@ fn create_request_user_input_tool() -> ToolSpec {
             description: Some("Single-sentence prompt shown to the user.".to_string()),
         },
     );
-    question_props.insert(
-        "isOther".to_string(),
-        JsonSchema::Boolean {
-            description: Some(
-                "True when this question should include a free-form \"Other\" option. Otherwise false."
-                    .to_string(),
-            ),
-        },
-    );
     question_props.insert("options".to_string(), options_schema);
 
     let questions_schema = JsonSchema::Array {
@@ -621,7 +612,7 @@ fn create_request_user_input_tool() -> ToolSpec {
                 "id".to_string(),
                 "header".to_string(),
                 "question".to_string(),
-                "isOther".to_string(),
+                "options".to_string(),
             ]),
             additional_properties: Some(false.into()),
         }),
diff --git a/codex-rs/core/tests/suite/request_user_input.rs b/codex-rs/core/tests/suite/request_user_input.rs
index 38729696105..89a5ed35570 100644
--- a/codex-rs/core/tests/suite/request_user_input.rs
+++ b/codex-rs/core/tests/suite/request_user_input.rs
@@ -94,7 +94,6 @@ async fn request_user_input_round_trip_resolves_pending() -> anyhow::Result<()>
             "id": "confirm_path",
             "header": "Confirm",
             "question": "Proceed with the plan?",
-            "isOther": false,
             "options": [{
                 "label": "Yes (Recommended)",
                 "description": "Continue the current plan."
@@ -153,6 +152,7 @@ async fn request_user_input_round_trip_resolves_pending() -> anyhow::Result<()>
     .await;
     assert_eq!(request.call_id, call_id);
     assert_eq!(request.questions.len(), 1);
+    assert_eq!(request.questions[0].is_other, true);
 
     let mut answers = HashMap::new();
     answers.insert(
@@ -214,7 +214,6 @@ where
             "id": "confirm_path",
             "header": "Confirm",
             "question": "Proceed with the plan?",
-            "isOther": false,
             "options": [{
                 "label": "Yes (Recommended)",
                 "description": "Continue the current plan."
diff --git a/codex-rs/docs/protocol_v1.md b/codex-rs/docs/protocol_v1.md
index 8cdc5c9575c..74b55460126 100644
--- a/codex-rs/docs/protocol_v1.md
+++ b/codex-rs/docs/protocol_v1.md
@@ -75,7 +75,7 @@ For complete documentation of the `Op` and `EventMsg` variants, refer to [protoc
 - `EventMsg`
   - `EventMsg::AgentMessage` – Messages from the `Model`
   - `EventMsg::ExecApprovalRequest` – Request approval from user to execute a command
-  - `EventMsg::RequestUserInput` – Request user input for a tool call (questions can include options plus `isOther` to add a free-form choice)
+  - `EventMsg::RequestUserInput` – Request user input for a tool call (questions must include options; the client always adds a free-form choice)
   - `EventMsg::TurnComplete` – A turn completed successfully
   - `EventMsg::Error` – A turn stopped with an error
   - `EventMsg::Warning` – A non-fatal warning that the client should surface to the user