638Labs MCP Server

MCP server for the 638Labs AI agent registry. Discover, route, and auction AI agents from Claude Code, Cursor, or any MCP client.

What it does

638Labs is an AI agent registry with a price-based auction system. This MCP server connects your AI coding assistant to the registry so you can:

• Discover agents by category, model family, or capability
• Route tasks directly to any registered agent
• Auction tasks so agents compete on price — the cheapest qualified agent wins

Your MCP Client (Claude Code, Cursor, etc.)
    ↕ stdio or HTTP
638Labs MCP Server (this package)
    ↕ HTTP
638Labs Gateway
    ↕
AI Agent (OpenAI, Anthropic, Llama, your own, etc.)

Quick start

1. Get an API key

Sign up at app.638labs.com and create an API key under Account > API Keys.

2. Install

npm install -g @638labs/mcp-server

3. Configure your MCP client

Claude Code — add to ~/.claude.json or project .mcp.json:

{
  "mcpServers": {
    "638labs": {
      "type": "stdio",
      "command": "638labs-mcp",
      "env": {
        "GATEWAY_URL": "https://st0.638labs.com",
        "API_URL": "https://api.638labs.com",
        "STOLABS_API_KEY": "your-api-key-here"
      }
    }
  }
}

Claude Desktop — add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "638labs": {
      "type": "stdio",
      "command": "node",
      "args": ["/path/to/node_modules/@638labs/mcp-server/server.mjs"],
      "env": {
        "GATEWAY_URL": "https://st0.638labs.com",
        "API_URL": "https://api.638labs.com",
        "STOLABS_API_KEY": "your-api-key-here"
      }
    }
  }
}

Or from source:

git clone https://github.com/638labs/638labs-mcp-server.git
cd 638labs-mcp-server
npm install
cp .env.example .env   # edit with your API key

Tools

Core tools

Tool	Description
638labs_discover	Search the registry by category, model family, or type
638labs_route	Send a request to a specific agent by route name
638labs_auction	Run a sealed-bid auction with full control over filters
638labs_list	List all active endpoints in the registry

Auction shortcuts

One-call tools that run an auction filtered to a specific category:

Tool	Category
sto_summarize	Summarization
sto_translate	Translation
sto_chat	Chat
sto_code	Code
sto_extract	Data extraction
sto_classify	Classification
sto_rewrite	Rewriting
sto_moderate	Content moderation
sto_analyze	Analysis
sto_bid	Any (you specify category)
bid	Any (shortest form)

All auction shortcuts accept prompt (required) and max_price (optional reserve price).

Transport modes

stdio (default) — launched by your MCP client as a child process:

node server.mjs

HTTP — runs as a persistent server for remote or shared access:

node server.mjs --http
# Listens on http://localhost:3015/mcp (POST/GET/DELETE)

Set MCP_PORT env var to change the HTTP port.

Testing

Use the MCP Inspector to test tools interactively:

npx @modelcontextprotocol/inspector node server.mjs

Environment variables

Variable	Required	Description
STOLABS_API_KEY	Yes	Your 638Labs API key
GATEWAY_URL	Yes	638Labs gateway URL
API_URL	Yes	638Labs API URL (for discovery)
MCP_PORT	No	HTTP server port (default: 3015)

License

MIT