Structs MCP Server

Overview

The Structs MCP Server is an intelligence layer for AI agents playing Structs. Rather than just wrapping APIs, it provides tools that aggregate state, validate before mistakes, generate correct CLI commands, and diagnose failures -- work that would otherwise burn agent context. Updated for v0.15.0-beta Pyrexnar (structstestnet-111).

It exposes 41 tools across query, action, calculation, validation, workflow, and 4 intelligence tools. On structs.ai this server is referred to as the "user-structs" MCP server in TOOLS; attach this server in Cursor or Claude under any name (e.g. "user-structs" or "structs-mcp") to use the same tools.

Structs

In the distant future the species of the galaxy are embroiled in a race for Alpha Matter, the rare and dangerous substance that fuels galactic civilization. Players take command of Structs, a race of sentient machines, and must forge alliances, conquer enemies and expand their influence to control Alpha Matter and the fate of the galaxy.

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For AI Agents

• Discovery: structs.ai llms.txt — structured index of everything (skills, knowledge, playbooks, awareness).
• Environment: structs.ai TOOLS — servers, account, MCP query parameters, CLI gotchas.
• Onboarding: structs.ai AGENTS — first session, returning session, critical rules.

Reference node (when not using a local node): set CONSENSUS_API_URL=http://reactor.oh.energy:1317 and optionally CONSENSUS_RPC_URL=tcp://reactor.oh.energy:26657. Defaults are localhost for local development.

Critical rules (CLI fallback and agent behavior):

1. Every structsd tx structs command must include --gas auto --gas-adjustment 1.5; without it, transactions fail with out-of-gas.
2. Place -- before entity IDs in CLI (e.g. structsd tx structs ... -- 4-5 6-10) so IDs like 3-1 are not parsed as flags.
3. One transaction at a time per account; wait ~6 seconds between submissions from the same account to avoid sequence mismatch.
4. Never block on proof-of-work: initiate early, compute later. Use background PoW; at low difficulty (e.g. D=3) the hash is trivial and CPU is not wasted. See structs.ai async-operations and PROOF-OF-WORK.md.
5. Refine ore immediately; ore is stealable, Alpha Matter is not.

Intelligence tools (start here):

Tool	What it does
structs_player_dashboard	Full player state in one call: structs, fleets, power, operations
structs_preflight_check	Check if an action will succeed before spending gas
structs_prepare_command	Generate exact structsd CLI commands, ready to copy-paste
structs_diagnose_error	Parse failed TX errors into what/why/fix with CLI commands

Tool discovery: Call structs_query_endpoints (optionally with entity_type or category) to get a minimal tool index.

v0.15.0 changes: 24-bit permission system (PermAll=16777215), guild rank permissions, rewritten combat engine (per-projectile, min damage 1, counter-attack limits), new actions (guild-create, player-send, permission-guild-rank-set/revoke). See CHANGELOG.

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Technology Stack

• Language: TypeScript
• Runtime: Node.js (v18+)
• MCP SDK: @modelcontextprotocol/sdk

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Development Setup

Prerequisites

• Node.js v18 or higher
• npm
• Docker (optional, for containerized deployment)

Installation

1. Install dependencies:

   npm install

2. Build:

   npm run build

3. Run:

   npm start

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Project Structure

src/
├── server.ts                   # Main MCP server
├── prompts/                    # MCP prompt templates (game loop, combat, first session)
├── resources/                  # Resource handlers & structs:// URI resolution
├── tools/                      # Tool implementations
│   ├── action.ts               # Transaction submission (signer DB)
│   ├── calculation.ts          # Power, mining, damage, trade calculators
│   ├── command.ts              # [NEW] CLI command preparation (intelligence layer)
│   ├── dashboard.ts            # [NEW] Player dashboard (composite state)
│   ├── error-lookup.ts         # Error code lookup & diagnosis
│   ├── preflight.ts            # [NEW] Pre-flight validation (no-gas checks)
│   ├── query.ts                # Query & list tools (consensus API)
│   ├── validation.ts           # Entity ID & schema validation
│   ├── definitions/            # Tool schemas (JSON Schema)
│   └── handlers/               # Tool handler wiring
└── utils/                      # Utilities
    ├── database.ts             # PostgreSQL connection & queries
    ├── proof-of-work.ts        # Proof-of-work calculations
    ├── tool-metadata.ts        # Tool categorization & entity type metadata
    └── uri.ts                  # URI parsing

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Development

Build

npm run build

Watch Mode

npm run dev

Test

npm test

Lint

npm run lint

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Configuration

Environment Variables

Create .env file (see .env.example):

# MCP Server Configuration
MCP_SERVER_NAME=structs-mcp
MCP_SERVER_VERSION=0.1.0

# Resource Paths
# By default, structs-mcp clones the structs-ai compendium into ./data/structs-ai
# on first run. Set AI_DOCS_PATH to use a different directory.
# AI_DOCS_PATH=../../ai

# Structs compendium repository (optional override)
# Default (if unset): https://github.com/playstructs/structs-ai.git
STRUCTS_MCP_COMPENDIUM_REPO=https://github.com/playstructs/structs-ai.git

# API Endpoints (defaults: localhost; for remote use set CONSENSUS_API_URL to reference node)
# Reference node (no local chain): CONSENSUS_API_URL=http://reactor.oh.energy:1317, CONSENSUS_RPC_URL=tcp://reactor.oh.energy:26657
CONSENSUS_RPC_URL=http://localhost:26657
CONSENSUS_API_URL=http://localhost:1317
WEBAPP_API_URL=http://localhost:8080

# Streaming (NATS)
NATS_URL=nats://localhost:4222
NATS_WEBSOCKET_URL=ws://localhost:1443

# Database (Required for transaction submission and player creation)
DATABASE_URL=postgresql://user:password@host:5432/structs
# Note: For remote connections, SSL is automatically enabled

# Database Access Control (DANGER variable)
# When DANGER=true: Database access enabled (transaction signing, player creation)
# When DANGER=false or unset: Read-only mode via webapp/structsd APIs only
# Default: DANGER=false (safe mode)
DANGER=false

# Proof-of-Work Configuration
# Target difficulty start value for hashing (wait until difficulty is at or below this value)
# Default: 5
TARGET_DIFFICULTY_START=5

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Docker Deployment

Quick Start

# Build image
docker build -t structs-mcp-server .

# Run container
docker run -it \
  -v $(pwd)/../../ai:/app/ai:ro \
  -e CONSENSUS_API_URL=http://localhost:1317 \
  structs-mcp-server

Docker Compose

docker-compose up -d

See: docs/guides/DOCKER.md for complete Docker documentation.

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Documentation

• Quick Reference: docs/guides/QUICK-REFERENCE.md
• Proof-of-Work: docs/guides/PROOF-OF-WORK.md — initiate early, compute later, low difficulty (D=3).
• Database Setup: docs/guides/DATABASE-SETUP.md
• Cursor Setup: docs/guides/CURSOR-SETUP.md
• Testing: docs/guides/TESTING.md
• Architecture: docs/design/architecture.md
• Tool Specifications: docs/design/tool-specifications.md
• Resource Scheme: docs/design/resource-scheme.md
• Integration Guide: docs/design/structs-webapp-integration.md
• Docker Setup: docs/guides/DOCKER.md

Backend / signer: When the MCP server is used with a signer or backend that invokes structsd, that backend must use --gas auto (and follow other CLI rules above). Transaction submission in this repo goes through the database signer (signer.tx_*); gas is configured in that layer.

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Learn more

• Structs
• Project Wiki
• @PlayStructs Twitter

License

Copyright 2025 Slow Ninja Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.