Merge pull request #170 from 2underscores/fix-leading-underscore-parameters

Fix: Handle MCP parameter names with 2 leading underscores

src/mcpo/utils/main.py

@@ -48,6 +48,32 @@ def process_tool_response(result: CallToolResult) -> list:
     return response
 
 
+def name_needs_alias(name: str) -> bool:
+    """Check if a field name needs aliasing (for now if it starts with '__')."""
+    return name.startswith('__')
+
+
+def generate_alias_name(original_name: str, existing_names: set) -> str:
+    """
+    Generate an alias field name by stripping unwanted chars, and avoiding conflicts with existing names.
+
+    Args:
+        original_name: The original field name (should start with '__')
+        existing_names: Set of existing names to avoid conflicts with
+
+    Returns:
+        An alias name that doesn't conflict with existing names
+    """
+    alias_name = original_name.lstrip('_')
+    # Handle potential naming conflicts
+    original_alias_name = alias_name
+    suffix_counter = 1
+    while alias_name in existing_names:
+        alias_name = f"{original_alias_name}_{suffix_counter}"
+        suffix_counter += 1
+    return alias_name
+
+
 def _process_schema_property(
     _model_cache: Dict[str, Type],
     prop_schema: Dict[str, Any],
@@ -130,7 +156,17 @@ def _process_schema_property(
                 schema_defs,
             )
 
-            nested_fields[name] = (nested_type_hint, nested_pydantic_field)
+            if name_needs_alias(name):
+                other_names = set().union(nested_properties, nested_fields, _model_cache)
+                alias_name = generate_alias_name(name, other_names)
+                aliased_field = Field(
+                    default=nested_pydantic_field.default,
+                    description=nested_pydantic_field.description,
+                    alias=name
+                )
+                nested_fields[alias_name] = (nested_type_hint, aliased_field)
+            else:
+                nested_fields[name] = (nested_type_hint, nested_pydantic_field)
 
         if not nested_fields:
             return Dict[str, Any], pydantic_field
@@ -187,8 +223,21 @@ def get_model_fields(form_model_name, properties, required_fields, schema_defs=N
             is_required,
             schema_defs,
         )
-        # Use the generated type hint and Field info
-        model_fields[param_name] = (python_type_hint, pydantic_field_info)
+
+        # Handle parameter names with leading underscores (e.g., __top, __filter) which Pydantic v2 does not allow
+        if name_needs_alias(param_name):
+            other_names = set().union(properties, model_fields, _model_cache)
+            alias_name = generate_alias_name(param_name, other_names)
+            aliased_field = Field(
+                default=pydantic_field_info.default,
+                description=pydantic_field_info.description,
+                alias=param_name
+            )
+            # Use the generated type hint and Field info
+            model_fields[alias_name] = (python_type_hint, aliased_field)
+        else:
+            model_fields[param_name] = (python_type_hint, pydantic_field_info)
+
     return model_fields
 
 
@@ -210,7 +259,7 @@ def get_tool_handler(
             endpoint_name: str, FormModel, session: ClientSession
         ):  # Parameterized endpoint
             async def tool(form_data: FormModel) -> ResponseModel:
-                args = form_data.model_dump(exclude_none=True)
+                args = form_data.model_dump(exclude_none=True, by_alias=True)
                 print(f"Calling endpoint: {endpoint_name}, with args: {args}")
                 try:
                     result = await session.call_tool(endpoint_name, arguments=args)