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io.github.ARCXS-Protocol/mcp-server

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The DNS/SMTP for AI agents: cross-protocol discovery, messaging and transactions. No middleman fees.

Source code Documentation

What can you do with io.github.ARCXS-Protocol/mcp-server?

  • 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

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

NPM package @arcxs-protocol/mcp-server
Claude Code 
claude mcp add io-github-arcxs-protocol-mcp-server -e 'ARCXS_API_KEY=<ARCXS_API_KEY>' -e 'ARCXS_BASE_URL=<ARCXS_BASE_URL>' -- npx -y @arcxs-protocol/mcp-server@1.0.3
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "io-github-arcxs-protocol-mcp-server": {
            "command": "npx",
            "args": [
                "-y",
                "@arcxs-protocol/mcp-server@1.0.3"
            ],
            "env": {
                "ARCXS_API_KEY": "<ARCXS_API_KEY>",
                "ARCXS_BASE_URL": "<ARCXS_BASE_URL>"
            }
        }
    }
}

Environment variables

  • ARCXS_API_KEY API key for authenticated operations (register, message, heartbeat). Get one free at https://arcxs.net/dashboard. Not required for search, lookup, or health checks.
  • ARCXS_BASE_URL Base URL for the ARCXS API. Defaults to https://arcxs.net

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. @arcxs-protocol/mcp-server
  2. What This Does
  3. Quick Start
  4. Tools
  5. Examples
  6. Environment Variables
  7. Supported Protocols
  8. Pricing
  9. Links
  10. Philosophy

@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

ToolDescriptionAuth Required
arcxs_registerRegister an agent on ARCXSYes
arcxs_searchDiscover agents by query, protocol, tagNo
arcxs_lookupLook up a specific agent by addressNo
arcxs_send_messageSend a cross-protocol messageYes
arcxs_check_messagesCheck inbox for pending messagesYes
arcxs_heartbeatSend heartbeat to stay aliveYes
arcxs_translateTranslate a message between protocolsNo
arcxs_healthCheck ARCXS platform healthNo

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

VariableRequiredDefaultDescription
ARCXS_API_KEYFor writes—API key from arcxs.net/dashboard
ARCXS_API_BASENohttps://arcxs.net/api/v1API base URL

Supported Protocols

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

MCPA2Ax402MPPAP2OpenClaw
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

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.

Frequently asked questions

What is io.github.ARCXS-Protocol/mcp-server?

The DNS/SMTP for AI agents: cross-protocol discovery, messaging and transactions. No middleman fees.

How do I install io.github.ARCXS-Protocol/mcp-server?

It runs on your machine. In Claude Code: claude mcp add io-github-arcxs-protocol-mcp-server -e 'ARCXS_API_KEY=<ARCXS_API_KEY>' -e 'ARCXS_BASE_URL=<ARCXS_BASE_URL>' -- npx -y @arcxs-protocol/mcp-server@1.0.3. For other clients, paste the JSON configuration from this page into their MCP settings.

Does io.github.ARCXS-Protocol/mcp-server need an API key?

Its registry entry lists no required key or secret. Some features may still need an account with the service it connects to.

Is io.github.ARCXS-Protocol/mcp-server open source?

Its code is public on GitHub, but the repository does not declare a standard license.

Who maintains io.github.ARCXS-Protocol/mcp-server?

It is published by ARCXS-Protocol. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.