diff --git a/src/writer/ai.py b/src/writer/ai.py
index bbdbbfbb8..557f6003d 100644
--- a/src/writer/ai.py
+++ b/src/writer/ai.py
@@ -90,17 +90,31 @@ class GraphTool(Tool):
     subqueries: bool
 
 
+class FunctionToolParameterMeta(TypedDict):
+    type: Union[
+        Literal["string"],
+        Literal["number"],
+        Literal["integer"],
+        Literal["float"],
+        Literal["boolean"],
+        Literal["array"],
+        Literal["object"],
+        Literal["null"]
+        ]
+    description: str
+
+
 class FunctionTool(Tool):
     callable: Callable
     name: str
     description: Optional[str]
-    parameters: Dict[str, Dict[str, str]]
+    parameters: Dict[str, FunctionToolParameterMeta]
 
 
 def create_function_tool(
     callable: Callable,
     name: str,
-    parameters: Optional[Dict[str, Dict[str, str]]] = None,
+    parameters: Optional[Dict[str, FunctionToolParameterMeta]] = None,
     description: Optional[str] = None
 ) -> FunctionTool:
     parameters = parameters or {}
@@ -1196,7 +1210,7 @@ def _register_callable(
             self,
             callable_to_register: Callable,
             name: str,
-            parameters: Dict[str, Dict[str, str]]
+            parameters: Dict[str, FunctionToolParameterMeta]
     ):
         """
         Internal helper function to store a provided callable
@@ -1266,7 +1280,9 @@ def _prepare_tool(
         Internal helper function to process a tool instance
         into the required format.
         """
-        def validate_parameters(parameters: Dict[str, Dict[str, str]]) -> bool:
+        def validate_parameters(
+                parameters: Dict[str, FunctionToolParameterMeta]
+        ) -> bool:
             """
             Validates the `parameters` dictionary to ensure that each key
             is a parameter name, and each value is a dictionary containing