Sts2mcp, developed by Gennadiyev, is an MCP server for Slay the Spire 2, designed to integrate AI agents with the game. This tool, primarily written in C# for its core mod component and Python for the server, enables AI to interact with the game's state and actions. It functions by exposing in-game data through a localhost REST API, allowing various AI assistants and LLM servers to connect and execute gameplay autonomously or analyze game states. Sts2mcp aims to provide a platform for AI research and agentic gameplay in Slay the Spire 2.

What does Sts2mcp connect to?

The Sts2mcp tool connects directly to the Slay the Spire 2 (STS2) game. It operates as a mod within STS2, exposing the game's internal state and available actions through a localhost REST API. Its primary function is as an MCP server, which stands for Model Context Protocol server. This categorization positions Sts2mcp as a core component for enabling full agentic runs within Slay the Spire 2, providing the necessary interface for AI agents to understand and interact with the game environment.

Core features and tools

Sts2mcp exposes several callable tools for AI interaction. These include general functions like get_profile(), get_compendium(), search_wiki(query, item_type, limit), list_profiles(), switch_profile(profile_id), and delete_profile(profile_id). For active gameplay, it offers get_game_state, combat_end_turn, play_card, menu_select, and choose_map_node. Multiplayer functionality is supported via tools prefixed with mp_, such as mp_get_game_state(format?) and mp_combat_play_card(card_index, target?), enabling AI participation in shared game environments.

Who is it for?

The primary audience for Sts2mcp is AI agents and researchers. It serves those interested in testing AI models and agents within gaming environments, specifically Slay the Spire 2. The tool supports full agentic runs, allowing AI to autonomously play the game, analyze its state, and interact with game elements. It also caters to developers building AI-driven solutions for game analysis or cooperative play. This is not the right fit if you are solely interested in playing Slay the Spire 2 manually without AI interaction.

How to get started

No credentials are required. The server communicates via a localhost REST API by starting an HTTP server on localhost:15526, with the port configurable via STS2_MCP.conf.

Use cases

• Autonomous gameplay: AI agents can fully play Slay the Spire 2 by fetching game state, processing it with an LLM, and executing game actions via the exposed REST API.
• Game state analysis: Agents can utilize tools like get_game_state, get_profile(), get_compendium(), and search_wiki() to gather detailed information about the game's current state and in-game entities.
• Multiplayer co-op with AI: The tool supports AI participation in multiplayer runs of Slay the Spire 2, enabling agents to interact within a shared game environment using mp_ prefixed tools.

Sts2mcp by Gennadiyev offers a crucial interface for integrating AI agents with Slay the Spire 2. It provides a localhost REST API to expose game state and actions, supporting autonomous gameplay, detailed game analysis, and even multiplayer co-op with AI. This tool is valuable for researchers and developers exploring AI in gaming. Its compatibility with various AI assistants and LLM servers makes it a versatile platform.