diff --git a/vllm_middleware.py b/vllm_middleware.py
index 96a2a38..2655dac 100644
--- a/vllm_middleware.py
+++ b/vllm_middleware.py
@@ -90,6 +90,41 @@ async def health():
 ERROR_LOG = os.environ.get("VLLM_SHIM_LOG", "/tmp/vllm-shim.log")
 
 
+def _fix_schema(schema: dict) -> bool:
+    """Recursively fix a JSON Schema dict: properties must be object, required must be list of strings."""
+    fixed = False
+    # Fix 'properties' — must be dict, not array/null
+    if "properties" in schema and not isinstance(schema["properties"], dict):
+        schema["properties"] = {}
+        fixed = True
+    # Fix 'required' — must be list of strings or absent
+    if "required" in schema and not isinstance(schema["required"], list):
+        del schema["required"]
+        fixed = True
+    # Recurse into every property value
+    if isinstance(schema.get("properties"), dict):
+        for val in schema["properties"].values():
+            if isinstance(val, dict):
+                if _fix_schema(val):
+                    fixed = True
+    # Recurse into items (for array-of-objects)
+    if isinstance(schema.get("items"), dict):
+        if _fix_schema(schema["items"]):
+            fixed = True
+    # Recurse into anyOf, allOf, oneOf
+    for key in ("anyOf", "allOf", "oneOf"):
+        if isinstance(schema.get(key), list):
+            for item in schema[key]:
+                if isinstance(item, dict):
+                    if _fix_schema(item):
+                        fixed = True
+    # Recurse into additionalProperties if it's a schema
+    if isinstance(schema.get("additionalProperties"), dict):
+        if _fix_schema(schema["additionalProperties"]):
+            fixed = True
+    return fixed
+
+
 def _dump_error(request_body: bytes, status_code: int, resp_headers: dict, resp_body_raw: bytes, path: str = ""):
     """Log full request + response payload when SGLang returns an error (4xx/5xx)."""
     try:
@@ -144,27 +179,18 @@ async def proxy(path: str, request: Request):
                     del data[key]
                     stripped_any = True
 
-            # Fix tool function parameters: must be object, not array/null/missing
-            # Also fix nested: parameters.properties must be object, not array
+            # Fix tool function parameters: recurse to fix ALL bad properties/required
             tools = data.get("tools")
             if isinstance(tools, list):
                 for tool in tools:
                     func = tool.get("function") if isinstance(tool, dict) else None
                     if not isinstance(func, dict):
                         continue
-                    params = func.get("parameters")
-                    if not isinstance(params, dict):
+                    if not isinstance(func.get("parameters"), dict):
                         func["parameters"] = {"type": "object", "properties": {}}
                         stripped_any = True
-                    else:
-                        # Fix nested: properties must be object, not array
-                        if not isinstance(params.get("properties"), dict):
-                            params["properties"] = {}
-                            stripped_any = True
-                        # required must be a list of strings if present
-                        if "required" in params and not isinstance(params["required"], list):
-                            del params["required"]
-                            stripped_any = True
+                    if _fix_schema(func["parameters"]):
+                        stripped_any = True
 
             if stripped_any:
                 body = json.dumps(data).encode()