From TUM's Chair of Geoinformatics (a 3DCityDB co-developer): query CityGML 3D city models in 3DCityDB v5 in plain language, covering both spatial and semantic attributes, with read-only SQL. Needs a deployed 3DCityDB database and Python; register it from the folder with your .env config.
tum-gis/3dcitydb-mcp-server18 