Nexa AI (Minecraft Mod + Paper Plugin)

Note: This page includes detailed information about the mod/plugin. If it feels too much, you can skip straight to using it. Just install the mod/plugin and run the command /nexa to get started right away.

Nexa AI adds an ai agent into Minecraft.

• Works as a Fabric / Forge mod (clients + servers)
• Also available as a Paper plugin

Players can talk to Nexa in chat and (with the right permissions) let it run server tools like teleporting, locating structures, changing weather/time, and more.

Features

• Chat with Nexa directly: /nexa <message>
• Agent modes:
  • Ask-before-act (default): privileged actions are previewed and require confirmation
  • Autonomous: Nexa can execute allowed steps automatically (guardrails still apply)
• Per-player request limits + global cooldown (server guardrails)
• Custom assistant name + personality prompt
• Fabric/Forge client UI (press N to open Nexa chat/config)
• Built-in tools (“function calling”) for server-aware actions and lookups
• Optional join/idle auto messages (can be turned off)
• Update notifications + feedback sending (via the proxy)

Supported Targets

• Fabric: Minecraft 1.21.11 and 1.20.1
• Forge: Minecraft 1.21.11 and 1.20.1
• Paper: Minecraft 1.21.11

Commands

Chat

• /nexa <message> — chat with Nexa
• /nexa confirm — approve queued actions (ask before act)
• /nexa cancel — cancel queued actions

Configuration

• /nex-config clearchat — clear your chat history
• /nex-config feedback <message> — send feedback (rate limited)
• /nex-config mode show — show your current mode
• /nex-config mode <ask|autonomous> — set your mode
• /nex-config limits status — show limits and cooldown
• /nex-config limits maxrequests <1..15> — set max requests (requires privileges)
• /nex-config limits cooldown <seconds> — set global cooldown (requires privileges)
• /nex-config custom name <name> — change assistant name (server: requires privileges)
• /nex-config custom prompt <prompt> — set personality prompt (server: requires privileges, max 1000 chars)
• /nex-config custom reset — reset name/prompt to defaults (server: requires privileges)
• /nex-config custom show — view your current custom settings
• /nex-config automessages enable|disable|status — toggle join/idle auto messages (server wide)

BYOK (Bring Your Own Key)

BYOK is per-player and bypasses the default proxy for chat calls.

• /nex-byok status — show BYOK status
• /nex-byok toggle enable|disable — enable/disable BYOK
• /nex-byok provider <google|openai|ollama|lmstudio|custom> — choose provider
• /nex-byok apikey <key> — set API key (cloud providers)
• /nex-byok endpoint <url|default> — set endpoint (local/custom providers)
• /nex-byok model <name> — set model name
• /nex-byok tools enable|disable — enable/disable tool calling (useful for local endpoints)
• /nex-byok test — test current BYOK config

Modes

Ask-before-act

Nexa proposes an action preview and waits for confirmation before running any privileged tool.

Approve via the clickable buttons in chat, or with /nexa confirm (deny with /nexa cancel).

privileged tools are queued for approval (30s) and can be approved via /nexa confirm.

Autonomous

Nexa can execute allowed tools without an explicit prompt. Guardrails still apply (cooldowns, limits, and required privileges).

AI Provider

Default AI Service

By default, Nexa uses the default services that are setup by me. It is free but you could expearence issue like rate limiting, overload, etc. So it is recommened to BYOK.

BYOK Mode

BYOK (Bring Your Own Key) lets each player use their own provider + key.

• Providers: Google, OpenAI, OpenAI-compatible (custom endpoint), Ollama, LM Studio
• Configure via /nex-byok ... (or the Fabric/Forge GUI)
• For best results, choose a model that supports tool calling / function calling

Note: BYOK settings (including API keys) are stored on the server in the world data file.

Permissions & Privileges

Nexa uses two permission nodes across all platforms:

• nexa.use — access to /nexa, /nex-config, and /nex-byok
• nexa.admin — administrative actions (guardrails + privileged tools)

Requirements & Installation

Java

• Minecraft 1.20.1: typically runs on Java 17
• Minecraft 1.21.11: typically runs on Java 21

Install

• Fabric: install Fabric Loader + Fabric API, then drop the nexa-fabric*.jar into .minecraft/mods/
• Forge: drop the nexa-forge*.jar into .minecraft/mods/
• Paper: drop nexa-paper-<version>.jar into plugins/ and restart

Tip: the server-side commands work with just the server install; the Fabric/Forge GUI is available when installed on the client.

Guardrails (Server)

• Agent mode: ASK_BEFORE_ACT or AUTONOMOUS
• Per-prompt request budget (maxrequests) and a global cooldown (cooldown)
• Privileged actions are previewed (and can be denied) in ask-before-act mode

Fair Use, Safety, and Privacy

• Community built: please don’t abuse the service (rate limits/guardrails exist for a reason).
• AI provider terms: when using the default service, prompts/responses are sent to Google Gemini. When using BYOK, your chosen provider’s terms/policies apply.
• Nexa can be wrong. Treat outputs as suggestions, especially for commands/actions.
• Harmful, abusive, illegal, or exploitative use is not tolerated. Repeated abuse may lead to denial of service.

Logging & Data

• Server/world file: Nexa stores persistent settings per-world in chatmc_locations.json (saved locations, mode/guardrails, BYOK config, etc.).
  • BYOK API keys are stored here (server-side). Only grant server file access to people you trust.
• Feedback: /nex-config feedback <message> sends your feedback message (and identifying metadata) to the proxy.

Support & Contributions

If you encounter issues, have feedback, or wish to contribute to Nexa AI, please join my Discord server and report there. Discord: https://discord.gg/Wvst4znsgk