Alphorn MCP Server

MCP server for Alphorn, the open-source notification router. It gives AI agents (Claude Code, Claude Desktop, Cursor, Codex, and any other MCP client) a send_notification tool, so an agent can tell you when a task finishes, fails, or needs your decision, on whatever channel you configured in Alphorn: Slack, Telegram, Discord, email, SMS, push, and more.

Works with the hosted service at app.alphorn.dev and with self-hosted Alphorn.

Setup

1. Create a webhook in Alphorn and copy its Endpoint URL, plus its API key if you switched on Require API key (docs).
2. Add the server to your MCP client with two environment variables:

Variable	Value
ALPHORN_WEBHOOK_URL	Endpoint URL, e.g. https://app.alphorn.dev/n/V1StGXR8_Z5jdHi6B-myT
ALPHORN_API_KEY	Webhook API key (alp_...). Leave unset if the webhook does not require one.

Claude Code

claude mcp add alphorn -s user \
  -e ALPHORN_WEBHOOK_URL=https://app.alphorn.dev/n/V1StGXR8_Z5jdHi6B-myT \
  -e ALPHORN_API_KEY=alp_... \
  -- npx -y @alphorn/mcp

Claude Desktop (one-click bundle)

Download alphorn.mcpb from the latest release and open it. Claude Desktop asks for the Endpoint URL and API key.

Claude Desktop, Cursor, and other JSON-configured clients

Add to claude_desktop_config.json, ~/.cursor/mcp.json, or your client's MCP config:

{
  "mcpServers": {
    "alphorn": {
      "command": "npx",
      "args": ["-y", "@alphorn/mcp"],
      "env": {
        "ALPHORN_WEBHOOK_URL": "https://app.alphorn.dev/n/V1StGXR8_Z5jdHi6B-myT",
        "ALPHORN_API_KEY": "alp_..."
      }
    }
  }
}

OpenAI Codex CLI

# ~/.codex/config.toml
[mcp_servers.alphorn]
command = "npx"
args = ["-y", "@alphorn/mcp"]
env = { ALPHORN_WEBHOOK_URL = "https://app.alphorn.dev/n/V1StGXR8_Z5jdHi6B-myT", ALPHORN_API_KEY = "alp_..." }

Tool

send_notification

Argument	Type	Required	Description
message	string	yes	What happened and what the agent needs from you (max 4,000 characters)
title	string	no	Short title, e.g. my-app - tests passing (max 200 characters)
priority	integer 1-5	no	2 = finished, 3 = needs input, 4 = blocked or failed, 5 = urgent
tags	string[]	no	Tags to filter and route on in Alphorn, e.g. ["ai-agent", "completed"]

The tool wraps Alphorn's send endpoint. For direct HTTP use, see the API reference and the OpenAPI 3.1 specification.

Use Alphorn's filters to decide where each notification goes, for example SMS only for priority 4 and above.

Development

pnpm install
pnpm test   # builds, then runs the tests against a local fake endpoint

Releasing

1. Bump version in package.json, server.json (both fields), manifest.json, and VERSION in src/server.ts.
2. npm publish --access public
3. Push a v<version> tag (or run the Publish to MCP Registry workflow): it publishes server.json to the MCP Registry via GitHub OIDC
4. pnpm bundle, then attach alphorn.mcpb to a GitHub release

License

AGPL-3.0-or-later