Rendering

render_style, compare_styles and compare_renderers draw with a renderer from the toolsets that are on. The gl-js, native and martin toolsets each add one, and the tools take a renderer argument to choose between them. The first renderer toolset in --toolsets is the default.

MapLibre GL JS

The gl-js toolset draws with the MapLibre GL JS that is installed with the server, in a headless browser. It uses Google Chrome, and without Chrome the Chromium that Playwright installs. On a machine without a GPU, Chrome falls back to software WebGL, which is slower.

It waits until the map has loaded, for up to 30 seconds, and then reports the errors the map raised and the images the style uses but its sprite lacks. It reads PMTiles sources, with pmtiles:// URLs, as well as tiles over HTTP.

MapLibre Native

The native toolset draws with MapLibre Native, the engine of the MapLibre iOS and Android SDKs, through @maplibre/maplibre-gl-native. That package has builds for macOS, Windows and Ubuntu 24.04, and has to be installed next to the server:

npx -y -p maplibre-mcp -p @maplibre/maplibre-gl-native maplibre-mcp --toolsets style,gl-js,native

In a client's JSON configuration, that is:

{
  "mcpServers": {
    "maplibre": {
      "command": "npx",
      "args": ["-y", "-p", "maplibre-mcp", "-p", "@maplibre/maplibre-gl-native", "maplibre-mcp", "--toolsets", "style,gl-js,native"]
    }
  }
}

On Node.js 26, use @maplibre/maplibre-gl-native@next. On Ubuntu, the build needs these libraries:

sudo apt-get install libopengl0 libglx0 libjpeg-turbo8 libuv1t64 libx11-6 libxext6 libwebp7 libicu74 libpng16-16t64

It also needs a display, so on a server without one, start maplibre-mcp with xvfb-run -a.

MapLibre Native doesn't draw terrain, the sky or projections other than Mercator yet. When a style uses them, the result says so, so that a difference from GL JS isn't taken for a bug. The Native renderer here can't read PMTiles sources yet.

Martin

The martin toolset draws with a Martin tile server, which renders with MapLibre Native on Linux. It draws the styles Martin serves, so pass the style as a URL like http://localhost:3000/style/<id>. Martin picks up changes to its style files right away, so an agent can edit a style file and render it again.

Rendering needs a Martin build with it, like the nightly-full Docker image, and this in Martin's configuration:

styles:
  paths:
    - /path/to/styles
  rendering: true

martin_list_sources lists the sources, sprites, fonts and styles of the server at MARTIN_URL, or http://localhost:3000.

Camera and size

Without a camera in the call, the renderers use the center, zoom, bearing and pitch stored in the style. center, zoom, bearing and pitch override them. bounds fits the map to [west, south, east, north] instead, with 32 pixels of padding and at most zoom 18. The camera is worked out once and passed to every renderer, so comparisons line up.

render_style draws 800 by 600 pixels by default, and up to 2048 on each side. The comparisons draw each image 512 by 384 by default, and up to 1024 on each side.

Comparisons

compare_styles and compare_renderers return one image with three panels side by side. The third one shows the first image faded, with the pixels that differ in red. Pixels that differ only by antialiasing are marked in yellow and don't count, and small differences in color are ignored, with pixelmatch at a threshold of 0.1. The text gives the share of pixels that differ.

compare_renderers leaves out the attribution, since only GL JS draws it.