From 4cd162a1235682d78e0ad04ca5f27bcaeef2460e Mon Sep 17 00:00:00 2001
From: Anri Lombard <anri.m.lombard@gmail.com>
Date: Thu, 1 Jan 2026 01:21:37 +0200
Subject: [PATCH] chat: make tool description and parameters optional per
 OpenAI spec (#18478)

* chat: make tool description and parameters optional per OpenAI spec

Per the OpenAI API specification, both 'description' and 'parameters'
fields in tool function definitions are optional. Previously, the parser
would throw an exception if these fields were missing.

Attempts to fix #17667

* refactor: use value() for cleaner optional field access
---
 common/chat.cpp     |  4 ++--
 tests/test-chat.cpp | 24 ++++++++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/common/chat.cpp b/common/chat.cpp
index be44c8abb0..7e940695bd 100644
--- a/common/chat.cpp
+++ b/common/chat.cpp
@@ -380,8 +380,8 @@ std::vector<common_chat_tool> common_chat_tools_parse_oaicompat(const json & too
                 const auto & function = tool.at("function");
                 result.push_back({
                     /* .name = */ function.at("name"),
-                    /* .description = */ function.at("description"),
-                    /* .parameters = */ function.at("parameters").dump(),
+                    /* .description = */ function.value("description", ""),
+                    /* .parameters = */ function.value("parameters", json::object()).dump(),
                 });
             }
         }
diff --git a/tests/test-chat.cpp b/tests/test-chat.cpp
index a78627604e..a07c81fba6 100644
--- a/tests/test-chat.cpp
+++ b/tests/test-chat.cpp
@@ -724,6 +724,30 @@ static void test_tools_oaicompat_json_conversion() {
             "]"
         ),
         common_chat_tools_to_json_oaicompat<json>({special_function_tool}).dump(2));
+
+    {
+        auto tools_no_params = common_chat_tools_parse_oaicompat(json::parse(
+            R"([{"type": "function", "function": {"name": "test_func", "description": "A test"}}])"));
+        assert_equals((size_t) 1, tools_no_params.size());
+        assert_equals(std::string("test_func"), tools_no_params[0].name);
+        assert_equals(std::string("A test"), tools_no_params[0].description);
+        assert_equals(std::string("{}"), tools_no_params[0].parameters);
+    }
+    {
+        auto tools_no_desc = common_chat_tools_parse_oaicompat(json::parse(
+            R"([{"type": "function", "function": {"name": "test_func", "parameters": {"type": "object"}}}])"));
+        assert_equals((size_t) 1, tools_no_desc.size());
+        assert_equals(std::string("test_func"), tools_no_desc[0].name);
+        assert_equals(std::string(""), tools_no_desc[0].description);
+    }
+    {
+        auto tools_minimal = common_chat_tools_parse_oaicompat(json::parse(
+            R"([{"type": "function", "function": {"name": "test_func"}}])"));
+        assert_equals((size_t) 1, tools_minimal.size());
+        assert_equals(std::string("test_func"), tools_minimal[0].name);
+        assert_equals(std::string(""), tools_minimal[0].description);
+        assert_equals(std::string("{}"), tools_minimal[0].parameters);
+    }
 }
 
 static void test_template_output_parsers() {