---
title: Real-time change watcher
description: Monitor code changes and trigger documentation drift detection automatically.
---
The `change_watcher` MCP tool keeps documentation drift checks up to date by reacting to file changes, git hooks, or webhooks.
## Quick start
1. Start watching:
- Tool: `change_watcher`
- Input:
- `action`: `"start"`
- `projectPath`: absolute path to your repo
- `docsPath`: absolute path to your docs
- Optional: `watchPaths` (defaults to `src`), `debounceMs` (default `500`), `excludePatterns`.
2. Manual trigger:
- `action`: `"trigger"`
- Optional: `reason`, `files` (array of changed files).
3. Status/stop:
- `action`: `"status"` or `"stop"`.
## Git hook integration
For local workflows:
- Call `change_watcher` with `action: "install_hook"` to drop a `post-commit` hook that pings the watcher on commit.
## Webhook integration
For CI/CD events:
- Start the watcher with `webhookEndpoint` (e.g., `/hooks/documcp/change-watcher`), optional `port` (default `8787`), and optional `webhookSecret`.
- Send POST payloads with GitHub/GitLab events; supported triggers: push/post-commit, pull_request, merge/merge_request, manual.
## Configuration reference
```json
{
"watchPaths": ["src"],
"excludePatterns": ["**/node_modules/**", "**/.git/**", "**/.documcp/**"],
"debounceMs": 500,
"triggerOnCommit": true,
"triggerOnPR": true,
"webhookEndpoint": "/hooks/documcp/change-watcher",
"webhookSecret": "optional-shared-secret"
}
```
## Outputs
Each detection run reports:
- `snapshotId`: latest snapshot timestamp
- `driftResults`: prioritized drift results from the detector
- `changedSymbols`: symbol/category/impact summary
- `affectedDocs`: list of impacted documentation files
- `events`: the triggers that fired this run
