SkillFoxx

Geargrafx MCP Server

The Geargrafx emulator built-in MCP server: an agent debugs PC Engine games, inspects memory and sets breakpoints.

  • 261 ★ on the repository
  • Last commit
  • GPL-3.0
MCP serverOfficial

Extended access

Why this level

  • The agent controls game execution and can change memory of the emulated system.
  • The HTTP server listens on 127.0.0.1 only by default.
All reasons and checks

drhelius/geargrafxAuthor:Ignacio Sanchez

Install

Manual install

Text for your agent

Download the Geargrafx MCPB package for your platform from the releases page, install it in Claude Desktop or start the emulator with the `--mcp-stdio` flag and call the CPU status tool.

Access and checks

How we review

Extended accessThe tool runs code or makes network calls and only reads external data.

  • The agent controls game execution and can change memory of the emulated system.
  • The HTTP server listens on 127.0.0.1 only by default.

This is third-party code. Review the repository files before installing.

What it does

Geargrafx is an accurate cross-platform emulator of TurboGrafx-16, PC Engine, SuperGrafx and their CD and laser disc systems, written in C++. It embeds an MCP server for debugging and development with agents. The tools give full debugger access: CPU registers, memory, breakpoints and execution control, plus disassembly around the program counter or any address and views of RAM, VRAM, ROM and CD-ROM memory. The server shows the state of the HuC6280, HuC6270, HuC6260, HuC6202, PSG and CD-ROM chips, lists 64 sprites with images, keeps debug symbols and bookmarks and shows the call stack and input state. It starts with the `--mcp-stdio` or `--mcp-http` flags, and a windowless `--headless` mode exists. Claude Code and Codex connect through packaged MCPB files or directly.

Who it is for. PC Engine game developers and retro platform enthusiasts who need an agent to trace code and work through hardware.

Good fit when

  • An agent sets a breakpoint on a memory access and explains who writes to the target cell.
  • A subroutine disassembly has to be read to find where sprite rendering is called.
  • Sprites and video registers are inspected to find the cause of a graphics glitch.
  • The server runs windowless on a CI machine and serves state over HTTP.

Not a fit when

  • You need other platforms, while the emulator covers only the PC Engine family.
  • You have no game images and BIOS, and CD-ROM games need a System Card.
  • You need an exact hardware debugger on a real console.

Example request

Set a breakpoint on a write to address 0x2200, continue execution and show the disassembly around the stop.

MCP

Transport
stdio, http
Authentication
not required

Limitations

The emulator runs game images and needs a BIOS for CD-ROM games, with System Card 3.0 recommended. The user supplies images and BIOS, and the repository has none. The `chd`, `cue/bin`, `cue/img` and `cue/iso` formats are supported, and MP3 tracks are not. LaserActive needs a Japanese PAC-N1/PCE-LP1 or a US PAC-N10 BIOS. The HTTP server listens on `127.0.0.1:7777` by default. The project is GPL-3.0, and an agent with full memory access changes the game state.

How to disable. Remove the MCPB package in the client settings or the geargrafx entry from the MCP configuration. The emulator is removed like any program, and settings sit beside it in `--portable` mode.

FAQ

How do I start the Geargrafx MCP server?

Start the emulator with `--mcp-stdio` or `--mcp-http`. For HTTP the address and port are set with `--mcp-http-address` and `--mcp-http-port`, defaulting to 127.0.0.1:7777. The `--headless` mode runs without a window.

What are MCPB packages?

MCP Bundles that contain Geargrafx with its MCP configuration for clients that install bundles. They are built for Windows, macOS and Linux on x64 and ARM64 and are published in the MCP registry.

Are there agent skills?

Yes, two: `geargrafx-debugging` for debugging, tracing and hardware inspection and `geargrafx-romhacking` for memory work, translations and patches. They teach the agent how to use the emulator.

Which memory areas are available?

RAM, VRAM, ROM, CD-ROM RAM, Arcade Card RAM and more. The tools also give disassembly, bookmarks and debug symbols.

Does the emulator work in RetroArch?

Yes, the project has a libretro core. The built-in MCP server belongs to the desktop builds, and the core is described in the libretro documentation.

Discussion

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README in short

The emulator is distributed for Windows, macOS, Linux, BSD and RetroArch. A separate MCP_README file describes the packages, tools and client setup.

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