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Alphorn

Official registry Productivity

Let AI agents notify you on Slack, Telegram, email, SMS, or push via an Alphorn webhook.

Source code Website Documentation

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 @alphorn/mcp
Claude Code 
claude mcp add alphorn -e 'ALPHORN_WEBHOOK_URL=<your alphorn_webhook_url>' -e 'ALPHORN_API_KEY=<your alphorn_api_key>' -- npx -y @alphorn/mcp@0.1.1
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "alphorn": {
            "command": "npx",
            "args": [
                "-y",
                "@alphorn/mcp@0.1.1"
            ],
            "env": {
                "ALPHORN_WEBHOOK_URL": "<your alphorn_webhook_url>",
                "ALPHORN_API_KEY": "<your alphorn_api_key>"
            }
        }
    }
}

Environment variables

  • ALPHORN_WEBHOOK_URL required secret Webhook Endpoint URL, e.g. https://app.alphorn.dev/n/V1StGXR8_Z5jdHi6B-myT
  • ALPHORN_API_KEY secret Webhook API key (alp_...), if the webhook requires one

Documentation

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

Contents
  1. Alphorn MCP Server
  2. Setup
  3. Tool
  4. Development
  5. License

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:
VariableValue
ALPHORN_WEBHOOK_URLEndpoint URL, e.g. https://app.alphorn.dev/n/V1StGXR8_Z5jdHi6B-myT
ALPHORN_API_KEYWebhook 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
ArgumentTypeRequiredDescription
messagestringyesWhat happened and what the agent needs from you (max 4,000 characters)
titlestringnoShort title, e.g. my-app - tests passing (max 200 characters)
priorityinteger 1-5no2 = finished, 3 = needs input, 4 = blocked or failed, 5 = urgent
tagsstring[]noTags 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

Frequently asked questions

What is Alphorn?

Let AI agents notify you on Slack, Telegram, email, SMS, or push via an Alphorn webhook.

How do I install Alphorn?

It runs on your machine. In Claude Code: claude mcp add alphorn -e 'ALPHORN_WEBHOOK_URL=<your alphorn_webhook_url>' -e 'ALPHORN_API_KEY=<your alphorn_api_key>' -- npx -y @alphorn/mcp@0.1.1. For other clients, paste the JSON configuration from this page into their MCP settings.

Does Alphorn need an API key?

Yes. It expects ALPHORN_WEBHOOK_URL, ALPHORN_API_KEY, which you set in its configuration.

Is Alphorn open source?

Yes. Its code is on GitHub under the AGPL-3.0 license.

Who maintains Alphorn?

It is published by alphorn-dev. 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.