diff --git a/open-sse/translator/request/openai-responses.ts b/open-sse/translator/request/openai-responses.ts
index 357c6e6c..5c9147a2 100644
--- a/open-sse/translator/request/openai-responses.ts
+++ b/open-sse/translator/request/openai-responses.ts
@@ -10,8 +10,6 @@ import { generateToolCallId } from "../helpers/toolCallHelper.ts";
 
 type JsonRecord = Record<string, unknown>;
 
-const UNSUPPORTED_TOOLS = ["file_search", "code_interpreter", "web_search_preview"];
-
 function toRecord(value: unknown): JsonRecord {
   return value && typeof value === "object" && !Array.isArray(value) ? (value as JsonRecord) : {};
 }
@@ -47,14 +45,16 @@ export function openaiResponsesToOpenAIRequest(
   const root = toRecord(body);
   if (root.input === undefined) return body;
 
-  // Validate unsupported features - return clear errors instead of silent failure
+  // Validate tool types — only function tools can be translated to Chat Completions
   const tools = toArray(root.tools);
   if (tools.length > 0) {
     for (const toolValue of tools) {
       const tool = toRecord(toolValue);
-      if (UNSUPPORTED_TOOLS.includes(toString(tool.type))) {
+      const toolType = toString(tool.type);
+      // Allow: function tools, and tools already in Chat format (have .function property)
+      if (toolType && toolType !== "function" && !tool.function) {
         throw unsupportedFeature(
-          `Unsupported Responses API feature: ${toString(tool.type)} tool type is not supported by omniroute`
+          `Unsupported Responses API feature: ${toolType} tool type is not supported by omniroute`
         );
       }
     }
diff --git a/tests/unit/responses-translation-fixes.test.mjs b/tests/unit/responses-translation-fixes.test.mjs
index 129fc3ce..76df1146 100644
--- a/tests/unit/responses-translation-fixes.test.mjs
+++ b/tests/unit/responses-translation-fixes.test.mjs
@@ -214,3 +214,50 @@ test("Responses→Chat: built-in tool_choice type throws unsupported error", ()
     (err) => err.message.includes("web_search_preview")
   );
 });
+
+test("Responses→Chat: web_search tool type throws unsupported error", () => {
+  const body = {
+    model: "gpt-4",
+    input: "search for cats",
+    tools: [{ type: "web_search", search_context_size: "medium" }],
+  };
+  assert.throws(
+    () => openaiResponsesToOpenAIRequest(null, body, null, null),
+    (err) => err.message.includes("web_search")
+  );
+});
+
+test("Responses→Chat: computer tool type throws unsupported error", () => {
+  const body = {
+    model: "gpt-4",
+    input: "click button",
+    tools: [{ type: "computer" }],
+  };
+  assert.throws(
+    () => openaiResponsesToOpenAIRequest(null, body, null, null),
+    (err) => err.message.includes("computer")
+  );
+});
+
+test("Responses→Chat: mcp tool type throws unsupported error", () => {
+  const body = {
+    model: "gpt-4",
+    input: "hello",
+    tools: [{ type: "mcp", server_label: "test", server_url: "https://example.com" }],
+  };
+  assert.throws(
+    () => openaiResponsesToOpenAIRequest(null, body, null, null),
+    (err) => err.message.includes("mcp")
+  );
+});
+
+test("Responses→Chat: function tool type passes through", () => {
+  const body = {
+    model: "gpt-4",
+    input: "hello",
+    tools: [{ type: "function", name: "greet", parameters: {} }],
+  };
+  const result = openaiResponsesToOpenAIRequest(null, body, null, null);
+  assert.equal(result.tools.length, 1);
+  assert.equal(result.tools[0].type, "function");
+});