Safely get tool default version instead of using direct @ access.
See also
Other accessor functions:
sn_get_installed_versions(),
sn_get_tool(),
sn_get_tool_commands(),
sn_get_tool_name(),
sn_get_tool_versions(),
sn_get_toolbox_tools(),
sn_get_toolcall_outputs(),
sn_get_toolcall_runtime(),
sn_get_toolcall_status(),
sn_is_tool_installed(),
sn_is_toolcall_success()