diff --git a/codex-rs/core/src/model_family.rs b/codex-rs/core/src/model_family.rs
index 853a970ff..5dea1c016 100644
--- a/codex-rs/core/src/model_family.rs
+++ b/codex-rs/core/src/model_family.rs
@@ -183,7 +183,7 @@ pub fn find_family_for_model(slug: &str) -> Option<ModelFamily> {
             base_instructions: BASE_INSTRUCTIONS.to_string(),
             default_reasoning_effort: Some(ReasoningEffort::Medium),
             truncation_policy: TruncationPolicy::Bytes(10_000),
-            shell_type: ConfigShellToolType::ShellCommand,
+            shell_type: ConfigShellToolType::UnifiedExec,
             supports_parallel_tool_calls: true,
         )
 
diff --git a/codex-rs/core/src/tools/spec.rs b/codex-rs/core/src/tools/spec.rs
index b3d0330f8..d07c605e5 100644
--- a/codex-rs/core/src/tools/spec.rs
+++ b/codex-rs/core/src/tools/spec.rs
@@ -1426,6 +1426,24 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_exp_5_1_defaults() {
+        assert_model_tools(
+            "exp-5.1",
+            &Features::with_defaults(),
+            &[
+                "exec_command",
+                "write_stdin",
+                "list_mcp_resources",
+                "list_mcp_resource_templates",
+                "read_mcp_resource",
+                "update_plan",
+                "apply_patch",
+                "view_image",
+            ],
+        );
+    }
+
     #[test]
     fn test_codex_mini_unified_exec_web_search() {
         assert_model_tools(
diff --git a/codex-rs/core/tests/suite/model_tools.rs b/codex-rs/core/tests/suite/model_tools.rs
index e807ce7db..cb2c5725f 100644
--- a/codex-rs/core/tests/suite/model_tools.rs
+++ b/codex-rs/core/tests/suite/model_tools.rs
@@ -121,4 +121,19 @@ async fn model_selects_expected_tools() {
         ],
         "gpt-5.1 should expose the apply_patch tool",
     );
+    let exp_tools = collect_tool_identifiers_for_model("exp-5.1").await;
+    assert_eq!(
+        exp_tools,
+        vec![
+            "exec_command".to_string(),
+            "write_stdin".to_string(),
+            "list_mcp_resources".to_string(),
+            "list_mcp_resource_templates".to_string(),
+            "read_mcp_resource".to_string(),
+            "update_plan".to_string(),
+            "apply_patch".to_string(),
+            "view_image".to_string()
+        ],
+        "exp-5.1 should expose the apply_patch tool",
+    );
 }