diff --git a/server.py b/server.py
index 82dfe69..0f5d41b 100644
--- a/server.py
+++ b/server.py
@@ -183,7 +183,7 @@ async def list_collection_documents(
 
 
 @mcp.tool()
-async def outline_api_call(method: str, params: str = "{}") -> str:
+async def outline_api_call(method: str, params: str = "") -> str:
     """Execute a raw Outline API call for any endpoint.
 
     Use the 'outline://api-reference' resource to discover available methods
@@ -202,7 +202,7 @@ async def outline_api_call(method: str, params: str = "{}") -> str:
         - method='documents.delete', params='{"id": "document-uuid"}'
     """
     try:
-        parsed_params = json.loads(params) if params else {}
+        parsed_params = json.loads(params) if params and params.strip() else {}
     except json.JSONDecodeError as e:
         return json.dumps({"ok": False, "error": f"Invalid JSON params: {str(e)}"})