Returns the cost, in USD, of the external tools your agents call, per tool, split into time buckets (hourly, daily or monthly, depending on the length of the date range). Groups are named by tool ID. Tools with no cost in a bucket are left out of it. Use toolIds to keep only some tools. For one figure per group over the whole period, a far smaller answer over a long date range, use get_cost_by_tool_aggregated, which does not take toolIds.