diff --git a/src/claude_agent_sdk/__init__.py b/src/claude_agent_sdk/__init__.py
index 31bebd09..023e3209 100644
--- a/src/claude_agent_sdk/__init__.py
+++ b/src/claude_agent_sdk/__init__.py
@@ -278,6 +278,8 @@ async def list_tools() -> list[Tool]:
                                 properties[param_name] = {"type": "number"}
                             elif param_type is bool:
                                 properties[param_name] = {"type": "boolean"}
+                            elif param_type is list:
+                                properties[param_name] = {"type": "array"}
                             else:
                                 properties[param_name] = {"type": "string"}  # Default
                         schema = {