fuel-mcp-server

Fuel Network & Sway Language MCP Server

This project provides a Model Context Protocol (MCP) server for the Fuel Network and Sway Language ecosystem. It allows IDEs (like Cursor) to search and interact with Fuel documentation directly within the development environment.

The server indexes Fuel and Sway documentation into a local Vectra vector database using open-source embeddings (via Transformers.js) for powerful semantic search capabilities.

Features

• Local semantic search of docs.fuel.network content
• No Docker dependency - runs with just Bun
• Fast file-based vector storage with Vectra
• Enhanced result filtering and formatting
• Hybrid search with keyword fallback

Quick Install

# Clone the repo
git clone https://github.com/FuelLabs/fuel-mcp-server
cd fuel-mcp-server

# Install dependencies
bun install

# Index documentation
bun run src/indexer.ts ./docs

# Test search
bun run src/query.ts --run "What is FuelVM?"

# Start MCP server
bun run src/cli.ts

Usage

STDIO Transport (Default)

bun run src/cli.ts
# or explicitly
bun run src/cli.ts --transport stdio

HTTP Transport

bun run src/cli.ts --transport http --port 3500
# Server runs at http://127.0.0.1:3500/mcp
# Health check: http://127.0.0.1:3500/health

CLI Options

bun run src/cli.ts --help
bun run src/cli.ts --transport http --port 3500
bun run src/cli.ts --transport stdio

Claude/Cursor Integration

Add to your MCP config file:

{
  "mcpServers": {
    "fuel-server": {
      "command": "bun",
      "args": ["run", "/absolute/path/to/fuel-mcp-server/src/cli.ts", "--transport", "stdio"]
    }
  }
}

Project Structure

.
├── docs/                     # Markdown documentation files
├── src/
│   ├── cli.ts                # Main CLI entry point
│   ├── server.ts             # MCP server factory
│   ├── transports/
│   │   ├── stdio.ts          # STDIO transport
│   │   └── http.ts           # HTTP transport
│   ├── chunker.ts            # Markdown chunking logic
│   ├── indexer.ts            # Document indexing script
│   ├── query.ts              # Search query script
│   └── *.test.ts             # Test files
├── vectra_index/             # Local vector database (created after indexing)
├── package.json
└── README.md

Prerequisites

• Bun: Install from bun.sh

Usage

1. Index Documents

Place markdown files in ./docs or specify a different directory:

# Index docs in ./docs (default)
bun run src/indexer.ts

# Index custom directory
bun run src/indexer.ts /path/to/your/docs

# With custom settings
EMBEDDING_MODEL=Xenova/bge-small-en-v1.5 bun run src/indexer.ts ./docs

2. Search Documents

# Basic search
bun run src/query.ts --run "What is the FuelVM?"

# Custom number of results
NUM_RESULTS=10 bun run src/query.ts --run "smart contracts"

3. Run MCP Server

# Start MCP server (stdio-mode)
bun run src/cli.ts

# With HTTP transport
bun run src/cli.ts --transport http --port 3500

4. Run Tests

bun test

Environment Variables

Variable	Default	Description
VECTRA_INDEX_PATH	./vectra_index	Vector database location
EMBEDDING_MODEL	Xenova/all-MiniLM-L6-v2	Hugging Face model
CHUNK_SIZE	2000	Target tokens per chunk
NUM_RESULTS	5	Search results count
LOG_LEVEL		Set to debug for verbose output

Implementation Details

• Chunking: Preserves code blocks, splits by paragraphs with context awareness
• Indexing: Generates embeddings with enhanced metadata for better search
• Querying: Semantic search with quality filtering and keyword fallback
• MCP Server: Exposes search as tool via stdio communication
• Storage: File-based Vectra index (no external database required)

API

MCP Tools

searchFuelDocs

• query (string): Search query
• nResults (number, optional): Number of results (default: 5)
• includeScore (boolean, optional): Include relevance scores

provideStdContext

• Returns Sway standard library paths and types

Development

# Install dependencies
bun install

# Run tests
bun test

# Index sample docs
bun run src/indexer.ts ./docs

# Test search functionality
bun run src/query.ts --run "test query"

# Start MCP server for development (STDIO)
bun run src/cli.ts

# Start MCP server for development (HTTP)
bun run src/cli.ts --transport http --port 3500