diff --git a/src-tauri/src/models/agent.rs b/src-tauri/src/models/agent.rs
index b390c91..c199f8a 100644
--- a/src-tauri/src/models/agent.rs
+++ b/src-tauri/src/models/agent.rs
@@ -176,15 +176,15 @@ impl Agent {
         let now = chrono::Utc::now().to_rfc3339();
 
         if existing.is_default {
-            if existing.name != name || existing.role != role || existing.tool != tool {
+            if existing.name != name || existing.role != role {
                 return Err(rusqlite::Error::InvalidParameterName(
-                    "Default agents cannot change name, role, or tool".to_string(),
+                    "Default agents cannot change name or role".to_string(),
                 ));
             }
 
             conn.execute(
-                "UPDATE agents SET custom_prompt = ?1, updated_at = ?2 WHERE id = ?3",
-                params![custom_prompt, now, id],
+                "UPDATE agents SET tool = ?1, custom_prompt = ?2, updated_at = ?3 WHERE id = ?4",
+                params![tool.as_str(), custom_prompt, now, id],
             )?;
             return Ok(());
         }
@@ -308,7 +308,7 @@ mod tests {
     }
 
     #[test]
-    fn test_update_default_agent_allows_prompt_only() {
+    fn test_update_default_agent_allows_tool_and_prompt_only() {
         let conn = setup();
         let analyst = Agent::get_default_by_role(&conn, AgentRole::Analyst).unwrap();
 
@@ -323,19 +323,20 @@ mod tests {
         .unwrap_err();
         assert!(err
             .to_string()
-            .contains("Default agents cannot change name, role, or tool"));
+            .contains("Default agents cannot change name or role"));
 
         Agent::update(
             &conn,
             &analyst.id,
             &analyst.name,
             analyst.role.clone(),
-            analyst.tool.clone(),
+            AgentTool::ClaudeCode,
             "Prompt override",
         )
         .unwrap();
 
         let updated = Agent::get_by_id(&conn, &analyst.id).unwrap();
+        assert_eq!(updated.tool, AgentTool::ClaudeCode);
         assert_eq!(updated.custom_prompt, "Prompt override");
     }
 
diff --git a/src/components/agents/AgentForm.tsx b/src/components/agents/AgentForm.tsx
index 3c107c8..8af623e 100644
--- a/src/components/agents/AgentForm.tsx
+++ b/src/components/agents/AgentForm.tsx
@@ -82,7 +82,8 @@ export default function AgentForm() {
         {initializing && <div className="text-sm text-gray-500">Loading agent...</div>}
         {isEditing && isDefaultAgent && (
           <div className="rounded border border-blue-200 bg-blue-50 p-3 text-sm text-blue-700">
-            This is a default agent. Only its script/prompt can be modified.
+            This is a default agent. Its tool and script/prompt can be modified, but its name and
+            role are fixed.
           </div>
         )}
 
@@ -116,7 +117,6 @@ export default function AgentForm() {
           <select
             value={tool}
             onChange={(e) => setTool(e.target.value as AgentTool)}
-            disabled={isEditing && isDefaultAgent}
             className="w-full rounded border border-gray-300 px-3 py-2 text-sm focus:outline-none focus:ring-2 focus:ring-blue-500"
           >
             <option value="codex">Codex</option>