Adjust max tool name length

codex-rs/core/src/mcp_connection_manager.rs

@@ -32,7 +32,7 @@ use crate::config_types::McpServerConfig;
 /// OpenAI requires tool names to conform to `^[a-zA-Z0-9_-]+$`, so we must
 /// choose a delimiter from this character set.
 const MCP_TOOL_NAME_DELIMITER: &str = "__";
-const MAX_TOOL_NAME_LENGTH: usize = 64;
+const MAX_TOOL_NAME_LENGTH: usize = 25;
 
 /// Timeout for the `tools/list` request.
 const LIST_TOOLS_TIMEOUT: Duration = Duration::from_secs(10);
@@ -55,10 +55,14 @@ fn qualify_tools(tools: Vec<ToolInfo>) -> HashMap<String, ToolInfo> {
             let sha1 = hasher.finalize();
             let sha1_str = format!("{sha1:x}");
 
-            // Truncate to make room for the hash suffix
-            let prefix_len = MAX_TOOL_NAME_LENGTH - sha1_str.len();
-
-            qualified_name = format!("{}{}", &qualified_name[..prefix_len], sha1_str);
+            if MAX_TOOL_NAME_LENGTH > sha1_str.len() {
+                // Truncate to make room for the hash suffix
+                let prefix_len = MAX_TOOL_NAME_LENGTH - sha1_str.len();
+                qualified_name = format!("{}{}", &qualified_name[..prefix_len], sha1_str);
+            } else {
+                // Not enough space for the full hash; fall back to a truncated hash only
+                qualified_name = sha1_str[..MAX_TOOL_NAME_LENGTH].to_string();
+            }
         }
 
         if used_names.contains(&qualified_name) {
@@ -342,16 +346,10 @@ mod tests {
         let mut keys: Vec<_> = qualified_tools.keys().cloned().collect();
         keys.sort();
 
-        assert_eq!(keys[0].len(), 64);
-        assert_eq!(
-            keys[0],
-            "my_server__extremely_lena02e507efc5a9de88637e436690364fd4219e4ef"
-        );
+        assert_eq!(keys[0].len(), 25);
+        assert_eq!(keys[0], "1c3987bd9c50b826cbe168796");
 
-        assert_eq!(keys[1].len(), 64);
-        assert_eq!(
-            keys[1],
-            "my_server__yet_another_e1c3987bd9c50b826cbe1687966f79f0c602d19ca"
-        );
+        assert_eq!(keys[1].len(), 25);
+        assert_eq!(keys[1], "a02e507efc5a9de88637e4366");
     }
 }

codex-rs/justfile

@@ -28,4 +28,5 @@ fix:
     cargo clippy --fix --all-features --tests --allow-dirty
 
 install:
+    rustup show active-toolchain
     cargo fetch