STS2MCP
Full agentic runs for Slay the Spire 2. A mod that exposes in-game state, and the MCP server for the mod.
What is STS2MCP?
STS2MCP is a Model Context Protocol (MCP) server that allows AI assistants like Claude, Cursor, and VS Code to full agentic runs for slay the spire 2. a mod that exposes in-game state, and the mcp server for the mod.
Full agentic runs for Slay the Spire 2. A mod that exposes in-game state, and the MCP server for the mod.
This server falls under the Coding Agents category on MCPgee, the world's largest MCP server directory with 33,000+ servers.
Features
- Full agentic runs for Slay the Spire 2. A mod that exposes i
Use Cases
Maintainer
Works with
Installation
Manual Installation
npx sts2mcpConfiguration
Configuration Details
claude_desktop_config.json
Performance
Response Metrics
Resource Usage
How to Set Up and Use STS2MCP
STS2MCP is a mod and MCP server combination for Slay the Spire 2 that exposes the game's internal state to AI agents, enabling fully autonomous agentic gameplay runs. The mod injects an HTTP server into the game that reports real-time game state — cards in hand, current map, player health, relics, available actions — and the MCP server translates this into tools that AI assistants can call to play the game autonomously. Researchers and AI hobbyists use it to benchmark LLM decision-making, run experiments on game strategy, and watch AI agents navigate roguelike challenges without human input.
Prerequisites
- Slay the Spire 2 installed on Steam
- Python 3.10+ and uv (the Python package manager) installed
- The STS2MCP mod files (STS2_MCP.dll and STS2_MCP.json) downloaded from the GitHub releases page
- An MCP-compatible client such as Claude Desktop or Claude Code
- The game must be running with mods enabled before the MCP server can access game state
Download the STS2MCP mod files
Download the latest release from the STS2MCP GitHub releases page. You need STS2_MCP.dll and STS2_MCP.json.
# GitHub releases page:
# https://github.com/Gennadiyev/STS2MCP/releasesCopy mod files to the game's mods directory
Copy both files to the mods directory inside your Slay the Spire 2 installation. On macOS the path is inside the app bundle; create the mods folder if it does not exist.
# Windows: <Steam library>/steamapps/common/Slay the Spire 2/mods/
# macOS: SlayTheSpire2.app/Contents/MacOS/mods/ (create if needed)
# Linux: <Steam library>/steamapps/common/Slay the Spire 2/mods/Launch the game and enable the mod
Start Slay the Spire 2 via Steam, go to the mods settings screen, and enable the STS2MCP mod. The mod starts an HTTP server on localhost:15526 automatically when a run begins.
Clone the MCP server component
Clone the STS2MCP repository to get the Python MCP server that communicates with the in-game HTTP endpoint.
git clone https://github.com/Gennadiyev/STS2MCP.git
cd STS2MCPConfigure your MCP client
Add the STS2MCP Python server to your MCP client configuration. Use the absolute path to uv and to the mcp directory. On macOS, GUI-launched apps may not have the shell PATH, so use absolute paths.
{
"mcpServers": {
"sts2": {
"command": "/opt/homebrew/bin/uv",
"args": ["run", "--directory", "/path/to/STS2MCP/mcp", "python", "server.py"]
}
}
}Start a run in the game and connect
Begin a game run in Slay the Spire 2. Then ask your AI assistant to fetch the current game state. The AI can read game state, check the compendium, and take actions autonomously.
STS2MCP Examples
Client configuration
claude_desktop_config.json entry for the STS2MCP Python MCP server connecting to the in-game HTTP bridge.
{
"mcpServers": {
"sts2": {
"command": "/opt/homebrew/bin/uv",
"args": [
"run",
"--directory",
"/Users/yourname/STS2MCP/mcp",
"python",
"server.py"
]
}
}
}Prompts to try
Example prompts for letting your AI assistant play Slay the Spire 2 autonomously via STS2MCP.
- "Check the current game state and tell me what cards I have in hand and what actions are available"
- "Play the current combat optimally — choose the best card plays to survive and defeat the enemy"
- "Look at the current map and recommend the best path considering my current deck and relics"
- "Search the compendium for all relics that synergize with my current deck"
- "Take over the run from here — play autonomously until we win or die, reporting each major decision"Troubleshooting STS2MCP
MCP server cannot connect to the game on localhost:15526
The in-game HTTP server only runs while an active run is in progress. Make sure Slay the Spire 2 is running, the STS2MCP mod is enabled, and you have started (not just opened) a game run. Check that no firewall is blocking localhost connections on port 15526.
'uv: command not found' when the MCP client tries to start the server
GUI-launched MCP clients do not inherit your shell PATH. Use the absolute path to uv in the command field (e.g. /opt/homebrew/bin/uv on macOS with Homebrew, or /home/user/.local/bin/uv on Linux). Run 'which uv' in your terminal to find the correct path.
Mod does not appear in the game's mod list
Verify both STS2_MCP.dll and STS2_MCP.json are in the correct mods directory. On macOS, the mods folder is inside the .app bundle at SlayTheSpire2.app/Contents/MacOS/mods/ — this folder may need to be created manually. Ensure the game is fully restarted after copying the files.
Frequently Asked Questions about STS2MCP
What is STS2MCP?
STS2MCP is a Model Context Protocol (MCP) server that full agentic runs for slay the spire 2. a mod that exposes in-game state, and the mcp server for the mod. It connects AI assistants to external tools and data sources through a standardized interface.
How do I install STS2MCP?
Follow the installation instructions on the STS2MCP GitHub repository. Clone the repo, install dependencies, and add the server config to your AI client.
Which AI clients work with STS2MCP?
STS2MCP works with all major MCP-compatible AI clients including Claude Desktop, Claude Code, Cursor, VS Code (GitHub Copilot), Windsurf, and Cline.
Is STS2MCP free to use?
Yes, STS2MCP is open source and available under the MIT license. You can use it freely in both personal and commercial projects.
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Set Up STS2MCP in Your Editor
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Quick Config Preview
Add this to your claude_desktop_config.json or .cursor/mcp.json
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