diff --git a/src/tools/http_request.rs b/src/tools/http_request.rs
index 0c05dd0..be6f9ce 100644
--- a/src/tools/http_request.rs
+++ b/src/tools/http_request.rs
@@ -4,6 +4,7 @@ use async_trait::async_trait;
 use reqwest::header::HeaderMap;
 use serde_json::json;
 
+use crate::text::take_prefix_chars;
 use crate::tools::traits::{Tool, ToolResult};
 
 pub struct HttpRequestTool {
@@ -93,10 +94,10 @@ impl HttpRequestTool {
             return text.to_string();
         }
 
-        if text.len() > self.max_response_size {
+        if text.chars().count() > self.max_response_size {
             format!(
                 "{}\n\n... [Response truncated due to size limit] ...",
-                &text[..self.max_response_size]
+                take_prefix_chars(text, self.max_response_size)
             )
         } else {
             text.to_string()
@@ -437,4 +438,15 @@ mod tests {
     async fn test_blocks_local_tld() {
         assert!(is_private_host("service.local"));
     }
+
+    #[tokio::test]
+    async fn test_truncate_response_handles_multibyte_boundary() {
+        let tool = HttpRequestTool::new(vec!["*".to_string()], 3, 30, false);
+        let text = "a\u{1F642}bc";
+        let truncated = tool.truncate_response(text);
+        assert_eq!(
+            truncated,
+            "a\u{1F642}b\n\n... [Response truncated due to size limit] ..."
+        );
+    }
 }
diff --git a/src/tools/web_fetch.rs b/src/tools/web_fetch.rs
index 16adb87..113b62d 100644
--- a/src/tools/web_fetch.rs
+++ b/src/tools/web_fetch.rs
@@ -4,6 +4,7 @@ use async_trait::async_trait;
 use reqwest::header::HeaderMap;
 use serde_json::json;
 
+use crate::text::take_prefix_chars;
 use crate::tools::traits::{Tool, ToolResult};
 
 pub struct WebFetchTool {
@@ -50,10 +51,10 @@ impl WebFetchTool {
             return text.to_string();
         }
 
-        if text.len() > self.max_response_size {
+        if text.chars().count() > self.max_response_size {
             format!(
                 "{}\n\n... [Response truncated due to size limit] ...",
-                &text[..self.max_response_size]
+                take_prefix_chars(text, self.max_response_size)
             )
         } else {
             text.to_string()
@@ -383,4 +384,15 @@ mod tests {
         assert!(text.contains("Content"));
         assert!(!text.contains("color"));
     }
+
+    #[tokio::test]
+    async fn test_truncate_response_handles_multibyte_boundary() {
+        let tool = WebFetchTool::new(3, 30);
+        let text = "a\u{1F642}bc";
+        let truncated = tool.truncate_response(text);
+        assert_eq!(
+            truncated,
+            "a\u{1F642}b\n\n... [Response truncated due to size limit] ..."
+        );
+    }
 }