ChangeDetection.io MCP Server

An MCP (Model Context Protocol) server that gives AI agents native access to ChangeDetection.io — the open-source website change detection and monitoring platform.

Features

• Watch Management — Create, list, update, delete, and trigger rechecks on watches
• Change History — Browse snapshot history and get diffs between any two points in time
• Per-watch action fuse — get_snapshot_diff arms a configurable limit on follow-up mutating actions for that watch so one noisy page cannot cascade into unlimited rechecks or edits
• Tag Management — Organise watches with tags/groups
• Search — Full-text search through watches by URL or title
• System Info — Quick health and stats readout

Why This Exists

No MCP server existed for ChangeDetection.io despite it being one of the most popular self-hosted tools (31k+ GitHub stars). This server fills that gap, letting AI agents:

• "Watch this product page and notify me when it changes"
• "Show me all my failed watches"
• "What changed on this page yesterday?"
• "Set up a watch for this job listing"

Quick Start

Prerequisites

• A running ChangeDetection.io instance (self-hosted or SaaS)
• An API key from Settings → API

Installation

pip install changedetection-mcp

Configuration

Add to your MCP client config (Claude Desktop, Cursor, Hermes Agent, etc.):

{
  "mcpServers": {
    "changedetection": {
      "command": "changedetection-mcp",
      "env": {
        "CHANGEDETECTION_BASE_URL": "http://localhost:5000",
        "CHANGEDETECTION_API_KEY": "your-api-key-here"
      }
    }
  }
}

Usage with Hermes Agent

Create ~/.hermes/skills/changedetection/SKILL.md (see skill/ directory) or configure as an MCP server:

hermes mcp add changedetection --command "changedetection-mcp"
hermes config set changedetection.base_url "http://localhost:5000"
hermes config set changedetection.api_key "your-api-key"

API Coverage

Safety Fuse: Per-Watch Action Limit

When an agent asks for a page diff, that diff can prompt follow-up actions such as immediate rechecks, watch edits, or deletes. To stop one noisy site from triggering a cascade, get_snapshot_diff arms a per-watch fuse before returning.

By default, each diff allows 3 mutating MCP actions for that watch. The fuse applies to:

• recheck_watch
• update_watch
• delete_watch

After the budget is exhausted, those tools return a clear blocked message instead of calling the ChangeDetection.io API. The fuse is in-process and per watch UUID; watches without an armed fuse are unaffected.

Configuration:

# Default: 3. Set 0 to disable the fuse globally.
export CHANGEDETECTION_MCP_ACTION_LIMIT_PER_WATCH=3

Per call, override the default with the optional action_limit argument on get_snapshot_diff:

get_snapshot_diff(uuid="...", from_timestamp="previous", to_timestamp="latest", action_limit=1)

Use action_limit=0 to disable the fuse for that watch, or call get_snapshot_diff again with a higher value to re-arm it.

Development

git clone https://github.com/rusty4444/changedetection-mcp.git
cd changedetection-mcp
uv venv
source .venv/bin/activate
uv pip install -e ".[dev]"

License

MIT — see LICENSE.