diff --git a/+llms/+utils/errorMessageCatalog.m b/+llms/+utils/errorMessageCatalog.m
index 6915120..36fef5e 100644
--- a/+llms/+utils/errorMessageCatalog.m
+++ b/+llms/+utils/errorMessageCatalog.m
@@ -41,7 +41,7 @@
 catalog("llms:mustBeAssistantWithIdAndFunction") = "Field 'tool_call' must be a struct with fields 'id' and 'function'.";
 catalog("llms:mustBeAssistantWithNameAndArguments") = "Field 'function' must be a struct with fields 'name' and 'arguments'.";
 catalog("llms:assistantMustHaveTextNameAndArguments") = "Fields 'name' and 'arguments' must be text with one or more characters.";
-catalog("llms:mustBeValidIndex") = "Value is larger than the number of elements in Messages ({1}).";
+catalog("llms:mustBeValidIndex") = "Index exceeds the number of array elements. Index must be less than or equal to ({1}).";
 catalog("llms:stopSequencesMustHaveMax4Elements") = "Number of elements must not be larger than 4.";
 catalog("llms:endpointMustBeSpecified") = "Unable to find endpoint. Either set environment variable AZURE_OPENAI_ENDPOINT or specify name-value argument ""Endpoint"".";
 catalog("llms:deploymentMustBeSpecified") = "Unable to find deployment name. Either set environment variable AZURE_OPENAI_DEPLOYMENT or specify name-value argument ""Deployment"".";