GIS MCP Server

Instructions

Implementation Reference

• src/gis_mcp/rasterio_functions.py:447-539 (handler)

  The core handler function for the 'resample_raster' tool. It opens a source raster (local or URL), resamples it by a given scale_factor using the specified resampling method (e.g., nearest, bilinear), computes new dimensions and transform, and writes the result to a destination file using rasterio.

  @gis_mcp.tool()
  def resample_raster(
      source: str,
      scale_factor: float,
      resampling: str,
      destination: str
  ) -> Dict[str, Any]:
      """
      Resample a raster dataset by a scale factor and save the result.
      
      Parameters:
      - source:       local path or HTTPS URL of the source raster.
      - scale_factor: multiplicative factor for width/height 
                      (e.g., 0.5 to halve resolution, 2.0 to double).
      - resampling:   resampling method name: "nearest", "bilinear", "cubic", etc.
      - destination:  local filesystem path for the resampled raster.
      """
      try:
          import numpy as np
          import rasterio
          from rasterio.enums import Resampling
          from rasterio.transform import Affine
  
          # Strip backticks if present
          src_clean = source.replace("`", "")
          dst_clean = destination.replace("`", "")
  
          # Open source (remote or local)
          if src_clean.lower().startswith("https://"):
              src = rasterio.open(src_clean)
          else:
              src_path = os.path.expanduser(src_clean)
              if not os.path.isfile(src_path):
                  raise FileNotFoundError(f"Source raster not found at '{src_path}'.")
              src = rasterio.open(src_path)
  
          # Validate scale factor
          if scale_factor <= 0:
              raise ValueError("Scale factor must be positive.")
  
          # Compute new dimensions
          new_width  = int(src.width  * scale_factor)
          new_height = int(src.height * scale_factor)
  
          if new_width == 0 or new_height == 0:
              raise ValueError("Resulting raster dimensions are zero. Check scale_factor.")
  
          # Map resampling method string to Resampling enum
          resampling_enum = getattr(Resampling, resampling.lower(), Resampling.nearest)
  
          # Read and resample all bands
          data = src.read(
              out_shape=(src.count, new_height, new_width),
              resampling=resampling_enum
          )
  
          # Validate resampled data
          if data is None or data.size == 0:
              raise ValueError("No data was resampled.")
  
          # Calculate the new transform to reflect the resampling
          new_transform = src.transform * Affine.scale(
              (src.width  / new_width),
              (src.height / new_height)
          )
  
          # Update profile
          profile = src.profile.copy()
          profile.update({
              "height":    new_height,
              "width":     new_width,
              "transform": new_transform
          })
          src.close()
  
          # Ensure destination directory exists
          dst_path = os.path.expanduser(dst_clean)
          os.makedirs(os.path.dirname(dst_path) or ".", exist_ok=True)
  
          # Write the resampled raster
          with rasterio.open(dst_path, "w", **profile) as dst:
              dst.write(data)
  
          return {
              "status":      "success",
              "destination": str(dst_path),
              "message":     f"Raster resampled by factor {scale_factor} using '{resampling}' and saved to '{dst_path}'."
          }
  
      except Exception as e:
          # Log error and raise for MCP to report
          logger.error(f"Error resampling raster '{source}': {e}")
          raise ValueError(f"Failed to resample raster: {e}")

• src/gis_mcp/rasterio_functions.py:11-35 (registration)

  MCP resource that lists available rasterio operations, including 'resample_raster', serving as a discovery/registration mechanism for the tool.

  @gis_mcp.resource("gis://operation/rasterio")
  def get_rasterio_operations() -> Dict[str, List[str]]:
      """List available rasterio operations."""
      return {
          "operations": [
              "metadata_raster",
              "get_raster_crs",
              "clip_raster_with_shapefile",
              "resample_raster",
              "reproject_raster",
              "weighted_band_sum",
              "concat_bands",
              "raster_algebra",
              "compute_ndvi",
              "raster_histogram",
              "tile_raster",
              "raster_band_statistics",
              "extract_band",
              "zonal_statistics",
              "reclassify_raster",
              "focal_statistics",
              "hillshade",
              "write_raster"
          ]
      }

• src/gis_mcp/mcp.py:1-5 (helper)

  Definition of the gis_mcp FastMCP instance used for tool and resource registration via decorators (@gis_mcp.tool(), @gis_mcp.resource()). All tools in rasterio_functions.py are registered to this instance.

  # MCP imports using the new SDK patterns
  from fastmcp import FastMCP
  
  
  gis_mcp = FastMCP("GIS MCP")