# Memento MCP Server

Model Context Protocol (MCP) server for integrating Memento note-taking app with N8N, Claude Desktop, Cursor, and other MCP clients.

**Version 3.2.0** - Enhanced with error handling, observability, rate limiting, and input validation.

## Features

- ✅ **22 Tools** for notes, notebooks, labels, and reminders
- 🔒 **API Key Authentication** with secure storage
- 🚀 **Performance Optimized** with connection pooling and caching
- 📊 **Observability** with Prometheus metrics export
- 🛡️ **Input Validation** using Zod schemas
- ⏱️ **Rate Limiting** per-user and global
- 🚨 **Structured Error Handling** with detailed messages
- 📝 **Audit Logging** for compliance

## Quick Start

```bash
cd mcp-server
npm install
```

### stdio Mode (Claude Desktop, Cline)

```bash
npm start
# or
node index.js
```

Claude Desktop configuration:
```json
{
  "mcpServers": {
    "memento": {
      "command": "docker",
      "args": ["exec", "-i", "memento-mcp", "node", "index.js"]
    }
  }
}
```

### HTTP Streamable Mode (N8N, remote)

```bash
npm run start:http
# or
node index-sse.js
```

## Authentication

When `MCP_REQUIRE_AUTH=true` (default in Docker), all requests require an `x-api-key` header.

Generate API keys from the Memento web UI: **Settings > MCP**.

```bash
# Example: health check with API key
curl -H "x-api-key: mcp_sk_xxx" http://localhost:3001/health
```

## Available Tools (22)

### Notes (13)

| Tool | Description |
|------|-------------|
| `create_note` | Create a new note |
| `get_notes` | List notes (filterable) |
| `get_note` | Get a specific note by ID |
| `update_note` | Update an existing note |
| `delete_note` | Delete a note permanently |
| `search_notes` | Search notes by keyword |
| `move_note` | Move a note to a notebook |
| `toggle_pin` | Pin/unpin a note |
| `toggle_archive` | Archive/unarchive a note |
| `append_to_note` | Append content to a note |
| `find_and_update_note` | Find and update a note |
| `batch_move_notes` | Move multiple notes at once |
| `batch_delete_notes` | Delete multiple notes at once |

### Notebooks (6)

| Tool | Description |
|------|-------------|
| `create_notebook` | Create a notebook |
| `get_notebooks` | List all notebooks |
| `get_notebook` | Get notebook details |
| `update_notebook` | Update a notebook |
| `delete_notebook` | Delete a notebook |
| `reorder_notebooks` | Reorder notebooks |
| `get_notebook_hierarchy` | Get tree structure of notebooks |

### Labels (4)

| Tool | Description |
|------|-------------|
| `create_label` | Create a label |
| `get_labels` | List labels |
| `update_label` | Update a label |
| `delete_label` | Delete a label |

### Reminders (1)

| Tool | Description |
|------|-------------|
| `get_due_reminders` | Get due reminders |

### Utilities (2)

| Tool | Description |
|------|-------------|
| `export_notes` | Export notes as JSON |
| `import_notes` | Import notes from JSON |

## HTTP Endpoints

| Endpoint | Method | Description | Auth Required |
|----------|--------|-------------|---------------|
| `/` | GET | Server info | No |
| `/health` | GET | Health check | No |
| `/metrics` | GET | Prometheus metrics | No* |
| `/sessions` | GET | Active sessions | Yes |
| `/mcp` | GET/POST | Main MCP endpoint | Yes |
| `/sse` | GET/POST | Legacy redirect to `/mcp` | Yes |

*Metrics can be disabled with `MCP_ENABLE_METRICS=false`

## Configuration

| Variable | Default | Description |
|----------|---------|-------------|
| `PORT` | 3001 | Server port |
| `DATABASE_URL` | required | PostgreSQL connection string |
| `MCP_REQUIRE_AUTH` | false | Require x-api-key header |
| `MCP_API_KEY` | - | Static fallback API key |
| `MCP_LOG_LEVEL` | info | Log level (debug, info, warn, error, silent) |
| `MCP_REQUEST_TIMEOUT` | 30000 | Request timeout in ms |
| `MCP_RATE_LIMIT` | 100 | Requests per window per user |
| `MCP_RATE_LIMIT_WINDOW` | 60000 | Rate limit window in ms |
| `MCP_MAX_SESSIONS` | 500 | Maximum concurrent sessions |
| `MCP_SESSION_TTL` | 3600000 | Session TTL in ms |
| `MCP_ENABLE_METRICS` | true | Enable metrics endpoint |
| `MCP_ENABLE_AUDIT_LOG` | true | Enable audit logging |
| `MCP_MAX_REQUEST_SIZE` | 10485760 | Max request size in bytes (10MB) |
| `APP_BASE_URL` | http://localhost:3000 | Memento app URL |
| `USER_ID` | - | Optional user ID filter |
| `DB_CONNECTION_LIMIT` | 10 | Prisma connection pool limit |
| `DB_POOL_TIMEOUT` | 10 | Prisma pool timeout in seconds |

## Error Handling

All errors follow a structured format:

```json
{
  "_error": true,
  "code": -32602,
  "httpCode": 400,
  "message": "Invalid params",
  "description": "Invalid method parameter(s)",
  "detail": "Input validation failed",
  "field": "content",
  "category": "validation",
  "timestamp": "2026-05-24T12:00:00.000Z"
}
```

### Error Codes

| Code | HTTP | Name |
|------|------|------|
| -32700 | 400 | Parse error |
| -32600 | 400 | Invalid request |
| -32601 | 404 | Tool not found |
| -32602 | 400 | Invalid params |
| -32603 | 500 | Internal error |
| -32000 | 500 | Database error |
| 401 | 401 | Authentication failed |
| 403 | 403 | Forbidden |
| 429 | 429 | Rate limit exceeded |
| 408 | 408 | Request timeout |
| 409 | 409 | Conflict |
| 422 | 422 | Unprocessable entity |
| 503 | 503 | Service unavailable |

## Metrics

Prometheus-compatible metrics are available at `/metrics`:

```
# HELP mcp_requests_total Total number of requests
mcp_requests_total 1234

# HELP mcp_latency_ms Request latency in milliseconds
mcp_latency_ms{quantile="0.5"} 45
mcp_latency_ms{quantile="0.95"} 120
mcp_latency_ms{quantile="0.99"} 250

# HELP mcp_errors_total Total number of errors
mcp_errors_total{category="validation"} 5
mcp_errors_total{category="database"} 2

# HELP mcp_auth_total Authentication attempts
mcp_auth_total{result="success"} 500
mcp_auth_total{result="failure"} 10

# HELP mcp_sessions_active Active sessions
mcp_sessions_active 15
```

## N8N Integration

### MCP Client Node Configuration

1. Add a **MCP Client** node in N8N
2. Select **Streamable HTTP** as transport
3. Endpoint: `http://memento-mcp:3001/mcp` (Docker) or `http://YOUR_IP:3001/mcp`
4. Add **Header Auth**: `x-api-key` = your MCP API key

### Example Workflow: Create a note from email

```json
{
  "tool": "create_note",
  "arguments": {
    "title": "{{ $json.subject }}",
    "content": "{{ $json.body }}",
    "labels": ["email", "inbox"],
    "notebookId": "inbox-notebook-id"
  }
}
```

## Docker Deployment

```yaml
services:
  memento-mcp:
    build: ./mcp-server
    environment:
      DATABASE_URL: ${DATABASE_URL}
      MCP_REQUIRE_AUTH: "true"
      MCP_LOG_LEVEL: "info"
    ports:
      - "3001:3001"
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:3001/health"]
      interval: 30s
      timeout: 10s
      retries: 3
```

## Testing

```bash
# Run all tests
npm test

# Run performance tests
npm run test:perf

# Run connection tests
npm run test:connection

# Validate configuration
npm run validate
```

## Security Considerations

1. **Always use authentication in production** (`MCP_REQUIRE_AUTH=true`)
2. **Use HTTPS** when exposing the server over the internet
3. **Set appropriate rate limits** for your use case
4. **Monitor metrics** for unusual activity
5. **Keep dependencies updated** with `npm audit`
6. **Use environment variables** for sensitive configuration

## Troubleshooting

### Database connection failed

```
FATAL: Database connection failed
```

- Verify `DATABASE_URL` is correct and reachable
- Check database credentials and permissions
- Ensure database is running and accessible

### Rate limit exceeded

```
429 Too Many Requests
```

- Wait for the rate limit window to expire (check `Retry-After` header)
- Increase `MCP_RATE_LIMIT` if needed
- Use multiple API keys for different applications

### Authentication failed

```
401 Unauthorized
```

- Verify API key is correct and active
- Check that `MCP_REQUIRE_AUTH=true` if using API keys
- Ensure API key hasn't been revoked

## Development

```bash
# Run with debug logging
MCP_LOG_LEVEL=debug npm run dev

# Check configuration
npm run validate

# Run tests
npm test
```

## License

MIT