RCS X MCP Server

An MCP (Model Context Protocol) server that lets any AI assistant — ChatGPT, Claude, Cursor, Cline, Continue, Cody — compose, preview, validate, and send RCS Business Messages from inside the chat.

Tools

Related MCP server: Twilio SMS Server

Endpoints

Run locally

npm install
npx wrangler dev        # local dev server at http://localhost:8787
npm test                # 15 integration tests, all green

Deploy

npx wrangler deploy     # publishes to rcsx-mcp-server.<acct>.workers.dev/mcp

Use it from ChatGPT

1. Open ChatGPT → Settings → Connectors → Developer mode (toggle on; requires org-admin).

2. Add connector → URL: https://rcsx-mcp-server.<acct>.workers.dev/mcp → Label: RCS X.

3. In any chat: "Draft an RCS to +14155551234 promoting a 40% off Black Friday deal."

Use it from Claude Desktop

Edit ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "rcsx": {
      "command": "npx",
      "args": ["-y", "mcp-remote@latest", "https://rcsx-mcp-server.<acct>.workers.dev/mcp"]
    }
  }
}

Use it from Cursor

Settings → Features → Model Context Protocol → Add new global MCP server:

{
  "mcpServers": {
    "rcsx": {
      "url": "https://rcsx-mcp-server.<acct>.workers.dev/mcp"
    }
  }
}

Architecture

• Cloudflare Workers — single-isolate, edge-deployed, sub-100ms cold start.

• Stateless MCP transport — every request is independent; fresh McpServer + fresh WebStandardStreamableHTTPServerTransport per incoming POST (per the SDK's _hasHandledRequest contract).

• @modelcontextprotocol/sdk 1.29+ with full inputSchema + outputSchema on every tool (Apps SDK requirement) and proper destructiveHint / openWorldHint annotations.

• Zod 4 for schema validation. Tool implementations are pure functions that return MCP-shaped { content, structuredContent, _meta }.

Why stateless

In stateless mode, the MCP SDK requires a fresh Server + Transport per request — both because the transport can only handle one request (_hasHandledRequest flag) AND because a server can only be connected to one transport at a time. Tool registration is cheap (Zod schemas + JSON), so the trade-off favors correctness.

License

Apache-2.0 — see LICENSE.