diff --git a/open-sse/translator/helpers/claudeHelper.ts b/open-sse/translator/helpers/claudeHelper.ts
index b30ad23eac..9b77a12594 100644
--- a/open-sse/translator/helpers/claudeHelper.ts
+++ b/open-sse/translator/helpers/claudeHelper.ts
@@ -126,6 +126,15 @@ export function prepareClaudeRequest(body, provider = null) {
       }
     }
 
+    // Pass 1.4: Filter out tool_use blocks with empty names (causes Claude 400 error)
+    for (const msg of filtered) {
+      if (msg.role === "assistant" && Array.isArray(msg.content)) {
+        msg.content = msg.content.filter(
+          (block) => block.type !== "tool_use" || (block.name && block.name.trim())
+        );
+      }
+    }
+
     // Pass 1.5: Fix tool_use/tool_result ordering
     // Each tool_use must have tool_result in the NEXT message (not same message with other content)
     filtered = fixToolUseOrdering(filtered);
diff --git a/open-sse/translator/request/openai-to-claude.ts b/open-sse/translator/request/openai-to-claude.ts
index b7004276c0..cec2430ef2 100644
--- a/open-sse/translator/request/openai-to-claude.ts
+++ b/open-sse/translator/request/openai-to-claude.ts
@@ -228,7 +228,10 @@ function getContentBlocksFromMessage(msg, toolNameMap = new Map()) {
           });
         } else if (part.type === "tool_use") {
           // Tool name already has prefix from tool declarations, keep as-is
-          blocks.push({ type: "tool_use", id: part.id, name: part.name, input: part.input });
+          // CRITICAL: Skip tool_use blocks with empty name (causes Claude 400 error)
+          if (part.name && part.name.trim()) {
+            blocks.push({ type: "tool_use", id: part.id, name: part.name, input: part.input });
+          }
         }
       }
     } else if (msg.content) {
@@ -241,8 +244,12 @@ function getContentBlocksFromMessage(msg, toolNameMap = new Map()) {
     if (msg.tool_calls && Array.isArray(msg.tool_calls)) {
       for (const tc of msg.tool_calls) {
         if (tc.type === "function") {
+          // CRITICAL: Skip tool_calls with empty function name (causes Claude 400 error)
+          const fnName = tc.function?.name;
+          if (!fnName || !fnName.trim()) continue;
+
           // Apply prefix to tool name
-          const toolName = CLAUDE_OAUTH_TOOL_PREFIX + tc.function.name;
+          const toolName = CLAUDE_OAUTH_TOOL_PREFIX + fnName;
           blocks.push({
             type: "tool_use",
             id: tc.id,