diff --git a/dspy/adapters/chat_adapter.py b/dspy/adapters/chat_adapter.py
index 3242e95be..6683a0b9a 100644
--- a/dspy/adapters/chat_adapter.py
+++ b/dspy/adapters/chat_adapter.py
@@ -177,7 +177,22 @@ def parse_value(value, annotation):
     return TypeAdapter(annotation).validate_python(parsed_value)
 
 
-def format_turn(signature: SignatureMeta, values: Dict[str, Any], role, incomplete=False):
+def format_turn(signature: SignatureMeta, values: Dict[str, Any], role, incomplete=False) -> Dict[str, str]:
+    """
+    Constructs a new message ("turn") to append to a chat thread. The message is carefully formatted
+    so that it can instruct an LLM to generate responses conforming to the specified DSPy signature.
+
+    Args:
+      signature: The DSPy signature to which future LLM responses should conform.
+      values: A dictionary of field names (from the DSPy signature) to corresponding values that
+              should be included in the message.
+      role: The role of the message, which can be either "user" or "assistant".
+      incomplete: If True, indicates that output field values are present in the set of specified
+                  ``values``. If False, indicates that ``values`` only contains input field values.
+    Returns:
+      A chat message that can be appended to a chat thread. The message contains two string fields:
+      ``role`` ("user" or "assistant") and ``content`` (containing the message itself).
+    """
     content = []
 
     if role == "user":