pyxel-mcp

An MCP server for observing programs built with Pyxel. It runs trusted local scripts headlessly and returns structured state, pixels, assets, audio, and frame differences.

The server deliberately reports facts rather than a universal quality score. The agent using it chooses the checks that matter for the game.

Install

With Claude Code:

claude mcp add pyxel -- uvx pyxel-mcp

For another MCP client, run uvx pyxel-mcp install or add:

   {
     "mcpServers": {
       "pyxel": {
         "command": "uvx",
         "args": ["pyxel-mcp"]
       }
     }
   }

Restart the client after changing its configuration. The server writes this diagnostic to stderr:

[pyxel-mcp] starting - 8 tools

Python 3.11+ is required, and Pyxel >= 2.9.6 is installed as a dependency. Script tools execute local Python in subprocesses to isolate Pyxel state, but they do not sandbox untrusted code. See SECURITY.md.

Tools

Every script argument is a file path, not Python source.

Tool	Returns
`validate`	Syntax errors and recognizable Pyxel code patterns.
`run`	Headless frames, scheduled input, logs, and `state`, `screen_image`, `screen_grid`, or `video` snapshots.
`pyxel_info`	Installed versions, paths, examples, and resource URIs.
`read_palette`	Palette colors and image-bank indices in use.
`read_image`	Image-bank pixels and an optional PNG render.
`read_tilemap`	Tile coordinates, source bank, usage counts, bounds, and an optional render.
`read_audio`	A rendered sound or music WAV plus measurable audio data.
`diff_frames`	Pixel differences between two PNG files.

All tools declare input and output schemas. Every result includes ok and errors.

Example

Capture state and the screen when a condition first becomes true:

{
  "script": "/absolute/path/game.py",
  "frames": 600,
  "until": "score >= 1",
  "snapshots": [
    {"kind": "state", "frame": "end", "attrs": ["score", "player.x"]},
    {"kind": "screen_image", "frame": "end", "output": "/tmp/goal.png"}
  ]
}

Use absolute artifact paths. Read log even when ok is true, and inspect captured images directly when appearance matters.

Resources

pyxel://run-snapshots-schema — complete run.snapshots grammar.
pyxel://validation-patterns — categories reported by validate.
pyxel://palette/default — default palette table.
pyxel://examples/{name} — source for an example bundled with the installed Pyxel package; discover names with pyxel_info.

Full game-building guidance lives in the separate pyxel-skill project; this package contains only the MCP server.

Update

uvx caches packages. Force a refresh with:

uvx --refresh-package pyxel-mcp pyxel-mcp install

Troubleshooting

If tools do not appear, look for the starting - 8 tools diagnostic and restart the client.
If run fails, inspect errors, exit_status, and log.
If a validation category is unfamiliar, read pyxel://validation-patterns.

MCP Registry

mcp-name: io.github.kitao/pyxel-mcp

License

MIT — see LICENSE.

Pyxel MCP

README