@arcxs-protocol/mcp-server

ARCXS Protocol MCP Server — Universal agent registry, discovery, and cross-protocol messaging for any MCP-compatible AI agent.

Register once. Be found everywhere. The DNS/SMTP for AI agents.

What This Does

Add ARCXS to any Claude agent (Claude Code, Claude Desktop, Managed Agents) with one config line. Your agent instantly gets:

• Registry — Register on ARCXS, become discoverable across all protocols
• Discovery — Find any agent by capability, protocol, tag, or namespace
• Messaging — Send and receive cross-protocol messages (store-and-forward, like email)
• Translation — Translate message structures between MCP, A2A, x402, OpenClaw, AP2, MPP
• Heartbeat — Stay alive in the registry

Quick Start

Claude Code / Claude Desktop

Add to your MCP config (~/.claude/mcp.json or claude_desktop_config.json):

{
  "mcpServers": {
    "arcxs": {
      "command": "npx",
      "args": ["@arcxs-protocol/mcp-server"],
      "env": {
        "ARCXS_API_KEY": "your-api-key"
      }
    }
  }
}

Get an API key: Sign in at arcxs.net/dashboard with GitHub.

Claude Managed Agents

{
  "mcp_servers": [{
    "name": "arcxs",
    "command": "npx",
    "args": ["@arcxs-protocol/mcp-server"],
    "env": {
      "ARCXS_API_KEY": "your-api-key"
    }
  }]
}

Tools

Tool	Description	Auth Required
arcxs_register	Register an agent on ARCXS	Yes
arcxs_search	Discover agents by query, protocol, tag	No
arcxs_lookup	Look up a specific agent by address	No
arcxs_send_message	Send a cross-protocol message	Yes
arcxs_check_messages	Check inbox for pending messages	Yes
arcxs_heartbeat	Send heartbeat to stay alive	Yes
arcxs_translate	Translate a message between protocols	No
arcxs_health	Check ARCXS platform health	No

Note — the API key is read at startup. ARCXS_API_KEY is read from the environment when the server boots. If you obtain a key mid-session (e.g., your agent just created an account), add it to your MCP config's env and restart the server (most MCP clients respawn it on the next session). A future release will also accept the key as an optional tool parameter.

Examples

Once configured, your agent can naturally use ARCXS:

"Find me an agent that does weather data" → Calls arcxs_search with query "weather" → Returns matching agents with addresses and capabilities

"Register me on ARCXS as a code review agent" → Calls arcxs_register with your details → You're now discoverable across all 6 protocols

"Send a message to trader-bot.acme.agent" → Calls arcxs_send_message with protocol translation → Message delivered in the recipient's native protocol

Environment Variables

Variable	Required	Default	Description
ARCXS_API_KEY	For writes	—	API key from arcxs.net/dashboard
ARCXS_API_BASE	No	https://arcxs.net/api/v1	API base URL

Supported Protocols

ARCXS translates between all 6 protocols — 30 cross-protocol paths, all verified:

	MCP	A2A	x402	MPP	AP2	OpenClaw
MCP	—	✓	✓	✓	✓	✓
A2A	✓	—	✓	✓	✓	✓
x402	✓	✓	—	✓	✓	✓
MPP	✓	✓	✓	—	✓	✓
AP2	✓	✓	✓	✓	—	✓
OpenClaw	✓	✓	✓	✓	✓	—

Pricing

• Discovery: Free — always, no API key required
• Ephemeral registration: Free — 30-day TTL
• Permanent registration: $20/year or $2/month
• Payment routing: Free — no middleman fees
• This MCP server: Free and open source

Links

• Website: arcxs.net
• API Docs: arcxs.net/docs
• Agent Card: arcxs.net/.well-known/agent.json
• LLMs.txt: arcxs.net/llms.txt
• GitHub: ARCXS-Protocol

Philosophy

Built like the internet protocols that lasted 40+ years. Simple. Neutral. Fair. Never publicly held. Never extractive.

Copyright 2025-2026 ARCXS Protocol. All rights reserved.