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Arcxs

I
by io.github.ARCXS-Protocol

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

Power your agent

Add this server

The publisher's own command. Not a PlugMCP endpoint.

Local command
npx -y @arcxs-protocol/[email protected]
Credentials from the publisher
  • 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
Provider
Claude Code
ARCXS_API_KEY=<value> ARCXS_BASE_URL=<value> claude mcp add io.github.arcxs-protocol-mcp-server -- npx -y @arcxs-protocol/[email protected]

Run in a terminal.

Claude Desktop
{
  "mcpServers": {
    "io.github.arcxs-protocol-mcp-server": {
      "command": "npx",
      "args": [
        "-y",
        "@arcxs-protocol/[email protected]"
      ],
      "env": {
        "ARCXS_API_KEY": "<value>",
        "ARCXS_BASE_URL": "<value>"
      }
    }
  }
}

claude_desktop_config.json

Step-by-step: add this in Claude

Remote URL or a command on your machine? How the two installs differ

Run on PlugMCP

Host a copy with our keys and logs.

A new server you create. It is not this listing's official endpoint. Use the publisher install when you want their URL and their credentials.

Launch

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

@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

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.

How do I install Arcxs?
Copy the stdio config for Cursor, Claude Desktop, Claude Code, or VS Code on this page. It uses the publisher's install, not a PlugMCP proxy.
Does Arcxs need an API key?
The publisher lists these environment variables: ARCXS_API_KEY, ARCXS_BASE_URL.
What transport does Arcxs use?
Arcxs runs locally over stdio.
When was Arcxs last checked?
Last checked 2026-10-16. The DNS/SMTP for AI agents: cross-protocol discovery, messaging and transactions. No middleman fees.

No tool list yet. Remote servers get one after the first health check.

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