Pyxel MCP server

pyxel-mcp

Let AI agents play, watch, and measure Pyxel games. pyxel-mcp is an MCP server that runs a Pyxel script headlessly, feeds it scheduled input, stops when a condition holds, and hands back the facts: screenshots, pixel grids, game state, assets, audio, and frame diffs.

Both images come from one run call against Pyxel's bundled 10platformer.py: 150 frames, right held from frame 0, jumps scheduled at frames 25, 70, and 110, a video snapshot, and an inline screenimage snapshot.

Why

An agent can write a Pyxel game in seconds, but it cannot open a window, press the arrow keys, or look at the screen. Editor-bound engines solve this with MCP servers that live inside the editor. Pyxel has no editor process to attach to, so pyxel-mcp drives the game itself:

• Headless and deterministic. Every call runs the script in a fresh subprocess with SDL dummy drivers, an optional RNG seed, and a frame budget. The same call gives the same frames on a laptop or in CI.
• Input as data. Buttons, axes, and mouse position are scheduled per frame, so a playtest is a JSON document the agent can rerun and extend.
• Stop on the event, not the clock. until="score >= 1" ends the run at the first frame where a game attribute holds, and "frame": "end" snapshots capture that moment.
• Facts, not scores. Tools report pixels, values, and measurements. Deciding whether the game is good stays with the agent and the person asking for it.
• See the frame in the result. inline: true returns a PNG as MCP image content, so the model looks at the screen without a second file read.

Install

Register the stdio server with your client:

claude mcp add --scope user pyxel -- uvx pyxel-mcp

codex mcp add pyxel -- uvx pyxel-mcp

gemini mcp add pyxel uvx pyxel-mcp

For Cursor (~/.cursor/mcp.json), a project-scoped Claude Code .mcp.json, or any other client that reads the common JSON format, add:

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

VS Code uses .vscode/mcp.json with a top-level servers key and "type": "stdio"; Codex CLI can also be configured in ~/.codex/config.toml as [mcp_servers.pyxel]. Run uvx pyxel-mcp install to print every variant.

Claude Code users can instead install the pyxel-skill plugin, which registers this server together with the skill that teaches agents how to use it:

claude plugin marketplace add kitao/pyxel-skill && claude plugin install pyxel@pyxel-skill

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.

How an agent uses it

Shortened. The full README is on GitHub.