GIS MCP Server

Instructions

Implementation Reference

• src/gis_mcp/pyproj_functions.py:109-152 (handler)

  The handler function for the 'get_available_crs' MCP tool. It fetches a list of available CRS from PyProj's EPSG database (limited to first 100 for performance), extracts name and type for each, with fallback to well-known CRS if none found.

  @gis_mcp.tool()
  def get_available_crs() -> Dict[str, Any]:
      """Get list of available CRS."""
      try:
          import pyproj
          from pyproj.database import get_codes
          from pyproj.enums import PJType
          
          crs_list = []
          # Get a sample of common EPSG codes (limit to avoid huge lists)
          epsg_codes = list(get_codes("EPSG", PJType.CRS))[:100]  # Limit to first 100 for performance
          
          for code in epsg_codes:
              try:
                  # Directly create CRS and get info without calling the tool function
                  crs_obj = pyproj.CRS.from_epsg(int(code))
                  crs_list.append({
                      "auth_name": "EPSG",
                      "code": str(code),
                      "name": crs_obj.name,
                      "type": crs_obj.type_name
                  })
              except Exception as ex:
                  # Skip invalid CRS codes
                  logger.debug(f"Skipping EPSG:{code}: {str(ex)}")
                  continue
          
          if not crs_list:
              # Fallback: return some well-known CRS
              well_known_crs = [
                  {"auth_name": "EPSG", "code": "4326", "name": "WGS 84", "type": "Geographic 2D CRS"},
                  {"auth_name": "EPSG", "code": "3857", "name": "WGS 84 / Pseudo-Mercator", "type": "Projected CRS"},
                  {"auth_name": "EPSG", "code": "4269", "name": "NAD83", "type": "Geographic 2D CRS"},
              ]
              crs_list = well_known_crs
          
          return {
              "status": "success",
              "crs_list": crs_list,
              "message": "Available CRS list retrieved successfully"
          }
      except Exception as e:
          logger.error(f"Error getting available CRS: {str(e)}")
          raise ValueError(f"Failed to get available CRS: {str(e)}")