The MCP aggregation tools do not write
What changes in The MCP aggregation tools do not write compared with MongoDB and what your application has to do.
This difference is of the Stronger guarantee kind.
What MongoDB does
aggregate in MongoDB MCP Server runs $out and $merge.
What TeselaDB does
The MCP tools aggregate and aggregate-db refuse $out and $merge.
What your application has to do
If your agent needs to store the result, let it use the write tools.