diff --git a/apps/ai-game-creator-shell/src-tauri/src/agent/direct_tool_bridge.rs b/apps/ai-game-creator-shell/src-tauri/src/agent/direct_tool_bridge.rs
index 286dd6bc6..b6db45647 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/agent/direct_tool_bridge.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/agent/direct_tool_bridge.rs
@@ -17,7 +17,7 @@ use crate::agent::tool::edit_image::error::EditImageError;
 use crate::agent::tool::editor_execute::error::{EditorExecuteError, EditorKind};
 use crate::agent::tool::environment_check::error::EnvironmentCheckError;
 use crate::agent::tool::error::{
-    DirectExecutionGateRejection, DirectTurnGateRejection, ProjectManifestRejection,
+    bounded_echo, DirectExecutionGateRejection, DirectTurnGateRejection, ProjectManifestRejection,
     ResourceCompletionRejection, ToolArgumentsRejection, ToolFailure, UnknownClientToolRejection,
 };
 use crate::agent::tool::generate_image::error::GenerateImageError;
@@ -4116,7 +4116,7 @@ async fn handle_direct_tool_bridge(
             )),
             _ => Err(ToolCallError::from(
                 &UnknownClientToolRejection {
-                    tool: request.tool.clone(),
+                    tool: bounded_echo(&request.tool),
                 },
             )),
         }
diff --git a/apps/ai-game-creator-shell/src-tauri/src/agent/tool/error.rs b/apps/ai-game-creator-shell/src-tauri/src/agent/tool/error.rs
index 8355e1812..43f9ee47f 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/agent/tool/error.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/agent/tool/error.rs
@@ -201,6 +201,7 @@ impl ToolFailure for DirectTurnGateRejection {
 /// 客户端工具桥收到没有登记过的工具名。
 ///
 /// 带上收到的名字：模型拼错工具名时要能从错误里看出自己写了什么，而不是只知道"不认识"。
+/// 名字在构造处就截到 [`BOUNDED_ECHO_MAX_CHARS`]，序列化后的诊断不会跟着被撑大。
 #[derive(serde::Serialize, Debug)]
 pub(crate) struct UnknownClientToolRejection {
     pub(crate) tool: String,