From e656b06882a9180cb5159ad3bf3fd15b08db4e33 Mon Sep 17 00:00:00 2001
From: Varun Vinayak Shenoy <shenoyvvarun@gmail.com>
Date: Fri, 22 Nov 2024 21:13:29 -0800
Subject: [PATCH] [Bugfix] Internal Server Error when tool_choice is incorrect.
 (#10567)

Signed-off-by: Varun Shenoy <varun.vinayak.shenoy@oracle.com>
Signed-off-by: Maxime Fournioux <55544262+mfournioux@users.noreply.github.com>
---
 tests/entrypoints/openai/test_chat.py | 14 ++++++++++++++
 vllm/entrypoints/openai/protocol.py   | 12 ++++++------
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/tests/entrypoints/openai/test_chat.py b/tests/entrypoints/openai/test_chat.py
index 843d15e768093..8d23a2be6f9bb 100644
--- a/tests/entrypoints/openai/test_chat.py
+++ b/tests/entrypoints/openai/test_chat.py
@@ -829,6 +829,20 @@ async def test_inconsistent_tool_choice_and_tools(client: openai.AsyncOpenAI,
                     "name": "nondefined_function_name"
                 }
             })
+    with pytest.raises(openai.BadRequestError):
+        await client.chat.completions.create(
+            model=MODEL_NAME,
+            messages=messages,
+            max_completion_tokens=1000,
+            tools=[{
+                "type": "function",
+                "function": {
+                    "name": "dummy_function_name",
+                    "description": "This is a dummy function",
+                    "parameters": sample_json_schema
+                }
+            }],
+            tool_choice={})
 
 
 @pytest.mark.asyncio
diff --git a/vllm/entrypoints/openai/protocol.py b/vllm/entrypoints/openai/protocol.py
index 9db5951e5fe5b..f343732174014 100644
--- a/vllm/entrypoints/openai/protocol.py
+++ b/vllm/entrypoints/openai/protocol.py
@@ -478,17 +478,17 @@ def check_tool_usage(cls, data):
             # it matches a valid tool
             if isinstance(data["tool_choice"], dict):
                 valid_tool = False
-                specified_function = data["tool_choice"]["function"]
+                specified_function = data["tool_choice"].get("function")
                 if not specified_function:
                     raise ValueError(
-                        "Incorrectly formatted `tool_choice`. Should be like "
-                        "`{\"type\": \"function\","
+                        "Expected field `function` in `tool_choice`."
+                        " Correct usage: `{\"type\": \"function\","
                         " \"function\": {\"name\": \"my_function\"}}`")
-                specified_function_name = specified_function["name"]
+                specified_function_name = specified_function.get("name")
                 if not specified_function_name:
                     raise ValueError(
-                        "Incorrectly formatted `tool_choice`. Should be like "
-                        "`{\"type\": \"function\", "
+                        "Expected field `name` in `function` in `tool_choice`."
+                        "Correct usage: `{\"type\": \"function\", "
                         "\"function\": {\"name\": \"my_function\"}}`")
                 for tool in data["tools"]:
                     if tool["function"]["name"] == specified_function_name: