Gearboy MCP — Use Cases, Install & Live Demo

Why use it

Key features

Embedded MCP server with stdio and HTTP transport for AI-assisted debugging
Advanced debugger: JIT disassembler, CPU/memory breakpoints, trace logging
VRAM viewer with tile, sprite, and palette inspection
Supports MBC1-7, HuC-1/3, MMM01, Pocket Camera, TAMA5 cartridge types
LCD ghosting and dot matrix visual effects mimicking original hardware

Live Demo

What it looks like in practice

gearboy-2.replay ▶ ready

0/0

Install

Pick your client

~/Library/Application Support/Claude/claude_desktop_config.json · Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "gearboy-2": {
      "command": "TODO",
      "args": [
        "See README: https://github.com/drhelius/Gearboy"
      ]
    }
  }
}

Open Claude Desktop → Settings → Developer → Edit Config. Restart after saving.

~/.cursor/mcp.json · .cursor/mcp.json

{
  "mcpServers": {
    "gearboy-2": {
      "command": "TODO",
      "args": [
        "See README: https://github.com/drhelius/Gearboy"
      ]
    }
  }
}

Cursor uses the same mcpServers schema as Claude Desktop. Project config wins over global.

VS Code → Cline → MCP Servers → Edit

{
  "mcpServers": {
    "gearboy-2": {
      "command": "TODO",
      "args": [
        "See README: https://github.com/drhelius/Gearboy"
      ]
    }
  }
}

Click the MCP Servers icon in the Cline sidebar, then "Edit Configuration".

~/.codeium/windsurf/mcp_config.json

{
  "mcpServers": {
    "gearboy-2": {
      "command": "TODO",
      "args": [
        "See README: https://github.com/drhelius/Gearboy"
      ]
    }
  }
}

Same shape as Claude Desktop. Restart Windsurf to pick up changes.

~/.continue/config.json

{
  "mcpServers": [
    {
      "name": "gearboy-2",
      "command": "TODO",
      "args": [
        "See README: https://github.com/drhelius/Gearboy"
      ]
    }
  ]
}

Continue uses an array of server objects rather than a map.

~/.config/zed/settings.json

{
  "context_servers": {
    "gearboy-2": {
      "command": {
        "path": "TODO",
        "args": [
          "See README: https://github.com/drhelius/Gearboy"
        ]
      }
    }
  }
}

Add to context_servers. Zed hot-reloads on save.

claude mcp add gearboy-2 -- TODO 'See README: https://github.com/drhelius/Gearboy'

One-liner. Verify with claude mcp list. Remove with claude mcp remove.

Use Cases

Real-world ways to use Gearboy

How to debug a Game Boy ROM with AI assistance using Gearboy

👤 Homebrew Game Boy developers and ROM hackers ⏱ ~30 min intermediate

When to use: You're developing a Game Boy homebrew ROM and need to debug runtime issues.

Prerequisites

Gearboy built with MCP support — Build from source following the GitHub README
A Game Boy ROM file (.gb or .gbc) — Your own homebrew ROM or a ROM you legally own

Flow

Load ROM and connect

Connect to the Gearboy MCP server and load my ROM. Show me the current CPU state and disassembly at the program counter.✓ Copied

→ CPU registers, flags, and disassembled instructions at PC
Set a breakpoint and investigate

Set a breakpoint at address 0x0150 (after the header). Step through execution and explain what each instruction does.✓ Copied

→ Step-by-step execution with instruction explanations
Inspect memory

Show me the contents of WRAM from 0xC000 to 0xC0FF. Are there any recognizable data structures?✓ Copied

→ Memory dump with analysis of data patterns

Outcome: A clear understanding of how the ROM executes, with bugs identified and explained.

Pitfalls

Breakpoints on frequently-hit addresses slow execution dramatically — Use conditional breakpoints or set them only when you're close to the bug

Combine with: filesystem

Learn Game Boy architecture interactively with AI and Gearboy

👤 Students learning retro console hardware and assembly ⏱ ~45 min intermediate

When to use: You want to understand how the Game Boy CPU, memory, and graphics work hands-on.

Prerequisites

Gearboy with MCP server — Build from source
A simple test ROM — Use a homebrew test ROM or Blargg's test ROMs

Flow

Explore the memory map

Show me the Game Boy memory map. Read the ROM header at 0x0100-0x014F and explain each field.✓ Copied

→ Annotated header with title, cartridge type, ROM/RAM sizes
Watch VRAM in action

Step through the VBlank interrupt handler and explain how tiles are loaded into VRAM.✓ Copied

→ Step-by-step explanation of tile loading with VRAM state

Outcome: Hands-on understanding of Game Boy hardware through interactive exploration.

Pitfalls

Assembly can be overwhelming for beginners — Start with simple test ROMs that exercise one hardware feature at a time

Combinations

Pair with other MCPs for X10 leverage

gearboy-2 + filesystem

Export memory dumps and debug logs for offline analysis

Dump the entire VRAM contents to a file and annotate the tile data layout.✓ Copied

Tools

What this MCP exposes

Tool	Inputs	When to call
pause/resume/step	none / step_count?	Control emulator execution
read_memory	address: int, size: int	Read emulator memory at any address
write_memory	address: int, data: bytes	Write to emulator memory
set_breakpoint	address: int, type?: str	Set a CPU or memory breakpoint
disassemble	address: int, count: int	Disassemble instructions at an address
get_cpu_state	none	Get current CPU registers and flags

Cost & Limits

What this costs to run

API quota: N/A — fully local
Tokens per call: 100–500 tokens per debug command
Monetary: Free and open source (MIT license)
Tip: Use targeted memory reads instead of full dumps to keep token usage low.

Security

Permissions, secrets, blast radius

Credential storage: N/A

Data egress: Fully local — no network calls

Troubleshooting

Common errors and fixes

MCP server not responding

Ensure Gearboy was built with MCP support enabled. Check that the server port (default 7777) is not in use.

Verify: curl http://localhost:7777/health

ROM fails to load

Verify the ROM file is a valid .gb or .gbc file. Check the file isn't corrupted.

Verify: Check the ROM header with a hex editor

Breakpoint never hits

Verify the address is in the execution path. Use the disassembler to check if code actually runs at that address.

Verify: Disassemble around the target address

Alternatives

Gearboy vs others

Alternative	When to use it instead	Tradeoff
Geargrafx	You want to debug PC Engine / TurboGrafx-16 ROMs instead of Game Boy	Different console, same MCP-enabled emulator approach by the same developer

More

Resources

📖 Read the official README on GitHub

🐙 Browse open issues

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