From b634e10b45cda0bc719674eaea6f2253e8a025e6 Mon Sep 17 00:00:00 2001
From: Howie Zhou <1996yeyan@gmail.com>
Date: Tue, 10 Jun 2025 13:48:49 -0700
Subject: [PATCH] Add JSON serialization for array and object parameters when
 converting tools (#8780)

---
 openhands/llm/fn_call_converter.py      |  5 +++-
 tests/unit/test_llm_fncall_converter.py | 38 +++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/openhands/llm/fn_call_converter.py b/openhands/llm/fn_call_converter.py
index 90827d10fb..64f67cf086 100644
--- a/openhands/llm/fn_call_converter.py
+++ b/openhands/llm/fn_call_converter.py
@@ -426,7 +426,10 @@ def convert_tool_call_to_string(tool_call: dict) -> str:
         ret += f'<parameter={param_name}>'
         if is_multiline:
             ret += '\n'
-        ret += f'{param_value}'
+        if isinstance(param_value, list) or isinstance(param_value, dict):
+            ret += json.dumps(param_value)
+        else:
+            ret += f'{param_value}'
         if is_multiline:
             ret += '\n'
         ret += '</parameter>\n'
diff --git a/tests/unit/test_llm_fncall_converter.py b/tests/unit/test_llm_fncall_converter.py
index 5bfc14b91e..52274f8abe 100644
--- a/tests/unit/test_llm_fncall_converter.py
+++ b/tests/unit/test_llm_fncall_converter.py
@@ -680,6 +680,44 @@ def example():
     print("hello")
     return True
 </parameter>
+</function>""",
+        ),
+        # Test case with list parameter value
+        (
+            [
+                {
+                    'index': 1,
+                    'function': {
+                        'arguments': '{"command": "test", "path": "/test/file.py", "tags": ["tag1", "tag2", "tag with spaces"]}',
+                        'name': 'test_function',
+                    },
+                    'id': 'test_id',
+                    'type': 'function',
+                }
+            ],
+            """<function=test_function>
+<parameter=command>test</parameter>
+<parameter=path>/test/file.py</parameter>
+<parameter=tags>["tag1", "tag2", "tag with spaces"]</parameter>
+</function>""",
+        ),
+        # Test case with dict parameter value
+        (
+            [
+                {
+                    'index': 1,
+                    'function': {
+                        'arguments': '{"command": "test", "path": "/test/file.py", "metadata": {"key1": "value1", "key2": 42, "nested": {"subkey": "subvalue"}}}',
+                        'name': 'test_function',
+                    },
+                    'id': 'test_id',
+                    'type': 'function',
+                }
+            ],
+            """<function=test_function>
+<parameter=command>test</parameter>
+<parameter=path>/test/file.py</parameter>
+<parameter=metadata>{"key1": "value1", "key2": 42, "nested": {"subkey": "subvalue"}}</parameter>
 </function>""",
         ),
     ],