mcp-postgis

A Model Context Protocol server that exposes PostGIS to MCP-aware clients (Claude Desktop, Claude Code).

Lets Claude introspect your spatial database, run safe spatial queries, and publish results as views that QGIS picks up automatically — so an analyst can describe a layer in plain language and have it land in their QGIS browser.

Install

pip install mcp-postgis     # or `uv tool install mcp-postgis`

Quick start (Docker PostGIS + Claude Desktop)

1. Run PostGIS:

   docker run --name postgis -e POSTGRES_PASSWORD=postgres \
     -p 5432:5432 -d postgis/postgis:16-3.4
   

2. Create a dedicated read-only role (see docs/security.md for read_write and admin variants):

   CREATE ROLE mcp_postgis_ro LOGIN PASSWORD 'change-me';
   GRANT CONNECT ON DATABASE mydb TO mcp_postgis_ro;
   GRANT USAGE ON SCHEMA public, app TO mcp_postgis_ro;
   GRANT SELECT ON ALL TABLES IN SCHEMA public, app TO mcp_postgis_ro;
   ALTER DEFAULT PRIVILEGES IN SCHEMA public, app
       GRANT SELECT ON TABLES TO mcp_postgis_ro;
   

3. Add to your claude_desktop_config.json:

   {
     "mcpServers": {
       "postgis": {
         "command": "uvx",
         "args": ["mcp-postgis"],
         "env": {
           "MCP_POSTGIS_DATABASE_URL": "postgresql://mcp_postgis_ro:change-me@localhost:5432/mydb",
           "MCP_POSTGIS_MODE": "read_only"
         }
       }
     }
   }
   

4. Restart Claude Desktop. The server's tools appear in the model picker.

Using with Claude Code (Linux/macOS/Windows)

Claude Desktop is macOS/Windows only — on Linux (or anywhere you use the CLI), register the server with Claude Code instead:

claude mcp add --transport stdio \
  --env MCP_POSTGIS_DATABASE_URL="postgresql://mcp_postgis_ro:change-me@localhost:5432/mydb" \
  --env MCP_POSTGIS_MODE=read_only \
  --scope user \
  postgis \
  -- uvx mcp-postgis

Restart claude, then /mcp lists the server and its tools. Use --scope user (not project) so your connection string isn't committed to a repo.

Modes

Tools

Introspection: list_schemas, list_tables, describe_table, list_geometry_columns, list_spatial_indexes, list_extensions

Query: execute_sql, explain, sample_table

Spatial analysis: features_in_bbox, features_in_polygon, nearest_features, within_distance, buffer, intersect_layers

Geometry operations: transform_srid, centroid, point_on_surface, area, length, simplify, is_valid, make_valid, bbox

Data quality: check_geometry_validity

Import / export: import_geojson (load a GeoJSON FeatureCollection into a table), export_geojson, export_wkt

Layer publishing (QGIS bridge): create_layer (with geometry_type filter), refresh_layer, list_layers, describe_layer, drop_layer

Resources: postgis://schemas, postgis://schema/{schema}/{table}, postgis://layers · Prompts: analyze-layer, nearest-things, within-radius, compare-layers

QGIS integration

After running the server in read_write mode and asking Claude to "publish that as a layer named hotels_near_coast", point QGIS at the same database (or use the same role). In the QGIS Browser → PostGIS → your connection, right-click → Refresh; the mcp_layers schema appears with hotels_near_coast inside it.

See docs/qgis-setup.md for screenshots.

License

MIT. Contributions welcome — please open an issue first to discuss bigger changes.