Summer Engine MCP guide
How to make games in Hermes Agent with Summer Engine
Give Hermes Agent the Summer Engine MCP tools so it can build playable game projects, run them, and read diagnostics in a real desktop engine. Summer Engine is the desktop game engine; Hermes Agent is the agent that drives it through MCP.
Summer is free for MCP use
Download the desktop engine and connect it to your agent. You are not paying Summer for the AI calls your existing subscription already covers.
Open Hermes Agent
Use the AI editor you already have. The setup command writes the MCP config and installs the Summer game-dev skills.
Run a Summer game
The agent writes code. Summer Engine shows the Summer game, runs Play mode, and helps inspect errors. Export still requires the target templates and toolchains.
Install
Connect Summer to Hermes Agent
- 1
Install Summer Engine
Downloads the desktop engine app, about 1 GB. Skip it if Summer Engine is already installed, or if you only need assets and video for a game built in another engine.
- 2
Sign in
Opens your browser once. The CLI and the engine share the session.
- 3
Connect Hermes Agent
Writes the summer-engine MCP config and installs the Summer game-dev skills.
- 4
Restart and build
Run /reload-mcp in Hermes Agent (or restart it).
Setup notes
The 2026 specifics.
Reload instead of restart
The setup command writes the summer-engine server to ~/.hermes/config.yaml and installs the skills to the shared ~/.agents/skills folder. Run /reload-mcp in Hermes Agent to pick it up without restarting.
Why this matters
Hermes Agent writes with your subscription. Summer Engine shows the game.
A chat agent alone can write files. With MCP, Hermes Agent gets tools for the running game engine, so it can inspect the project, run commands, and make changes that become playable inside Summer.