Comparator

The AI agent built for Minecraft.

Comparator brings a fully conversational AI agent to your Paper server; with multi-turn memory, built-in tools, and an API to extend it on your own.

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Features

🤖 Conversational AI Agent

Embed a fully conversational AI agent directly into your Minecraft server. Comparator maintains context across messages for natural, coherent dialogue; not just one-shot responses.

🔧 Built-In Tools

The agent can to more than just chat. Comparator ships with several built-in tools the AI can invoke to give accurate, grounded answers:

Tool	Description
Web Search	Searches the web for up-to-date information, so the agent isn't limited to its training data
Current Date	Retrieves the current date, helping the agent reason about how recent its knowledge is
Game Version	Fetches the server's running Minecraft version so answers are version-accurate
Player Info	Retrieves the player's surroundings, inventory, nearby entities, biome, game mode, and what they're looking at. This enables contextual in-game assistance

🌐 Embedded Web Panel

Comparator includes a built-in web panel served directly from the plugin via an embedded server. It gives server admins a live view into conversations, tool runs, and registered tools with real-time updates. No separate deployment needed; just configure the host and port in comparator.conf and run /comparator panel start to launch it.

🧩 Extensible Tool API

Third-party plugins can register their own tools using the Comparator API. Defining a tool is as simple as annotating a function:

@ToolFunction("give_item", "Gives an item to the requesting player")
suspend fun giveItem(
    @ToolParameter("The item to give") item: String,
    context: ToolContext
): GiveResult {
    val player = context.bukkitPlayer ?: throw ToolException("No player context", null)
    // ...
}

// Register during ToolRegistrationEvent
event.registry.register(tool(::giveItem))

The API handles parameter validation, type checking, serialization, and error reporting automatically. See the API docs for full details.

🔒 Designed for Responsible AI Use

Comparator was built with safety and transparency in mind. This sets it apart from plugins that simply wrap an AI API with no guardrails:

• Permission-gated access — All commands and public chat interactions respect Bukkit permissions, giving server admins fine-grained control over who can use the agent and who can manage it.
• Configurable system prompt — The agent's behavior, persona, and constraints are fully configurable. The default prompt explicitly instructs the agent to stay on-topic, avoid fabricating information, and flag when its knowledge may be outdated.
• Context scoping — Conversations are isolated per-player, per-console, and for public chat. A player cannot read or pollute another player's conversation history.
• Automatic context expiry — Conversation history expires after a configurable period of inactivity, limiting unintended data retention.
• Tool result and parameter validation — Tool inputs are validated against declared parameter types and constraints before execution. The agent cannot invoke a tool with malformed arguments.
• Queue-based message handling — Each conversation runs through a bounded channel. If a player floods the agent with messages, excess requests are rejected gracefully rather than queued unboundedly.
• Structured error handling — Tool failures are surfaced to the model as descriptive errors, not raw stack traces or internal state.

⚡ High-Performance, Non-Blocking Architecture

Built on Kotlin coroutines for fully non-blocking execution. AI requests, tool calls, and context operations never block the server thread, so the agent has no impact on server tick performance.

✨ Flexible AI Provider Support

Integrates with Ollama, supporting both cloud-hosted and self-hosted models. Configure your model, base URL, and optional API key in comparator.conf.

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Installation

1. Download the plugin .jar from Modrinth or GitHub Releases
2. Place the .jar in your server's plugins/ folder
3. Restart your server
4. Follow the quickstart guide to complete setup

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Usage

Ask in private (DM-style):

/ask <prompt>

Mention in public chat:

@bot <prompt>

For full usage information, see the documentation.

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Support

• Plugin Documentation
• API Documentation
• Discord
• GitHub Issues

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Contributing

Contributions are welcome!

1. Fork the repository
2. Create a feature branch: git checkout -b feature/my-feature
3. Commit your changes: git commit -m "Add my feature"
4. Push and open a Pull Request

Please follow the existing code style and include tests where applicable. For more details, see CONTRIBUTING.md.

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Credits

• Main icon: circuit by Skena Grafis from The Noun Project (CC BY 3.0)