log-reader-mcp: Cursor rule for Cursor

MCP Logging Workflow

This guide defines the standards for log management in a project using the MCP server. It is intended for the AI agent and anyone developing on this project.

Log Structure and Location

• Required folder: Every project must have a logs/ folder at the root.
• Log file: The main log file must be named logs.log and placed in this folder.

Log Format

• Structured JSON format: Each line in the logs.log file must be a JSON object following the schema below (see also the definition in @mcp-server.ts):

{
  "level": "INFO|WARN|ERROR|DEBUG|CRITICAL",
  "timestamp": "YYYY-MM-DDTHH:MM:SS.sssZ",
  "message": "string",
  "service_name": "string (optional)",
  "user_id": "string (optional)",
  "context": { ... } (optional),
  "event": { ... } (optional)
}

• Example:

{
  "level": "INFO",
  "timestamp": "2025-06-01T12:34:56.789Z",
  "message": "User login succeeded",
  "service_name": "auth",
  "user_id": "12345",
  "context": { "ip": "192.168.1.10" },
  "event": { "action": "login" }
}

• Schema compliance: Always use the project's logging utility function (or the MCP API) to ensure format compliance. Never write directly to the file without validation.

Using the read_log Tool

• MCP Tool: The server exposes the read_log tool to read the last lines of the log file, with optional time interval filtering.
• Main arguments:
  • lines: number of lines to read (default: 50)
  • start_time / end_time: optional ISO 8601 time bounds
• Log file: The server always uses the logs/logs.log file in the user's working directory.
• Example call:

{
  "tool": "read_log",
  "args": {
    "lines": 100,
    "start_time": "2025-06-01T00:00:00Z",
    "end_time": "2025-06-01T23:59:59Z"
  }
}

Use Cases

Here are several concrete examples of using logs and the read_log tool:

• Debugging a production error:
  • Read the last 200 lines of the log to identify a sequence of events leading to a critical error.
  • Filter logs over a specific time range to isolate an incident.
• Verifying a new feature implementation:
  • Check that expected events (e.g., user creation, payment validated) appear in the logs after a deployment.
• Security audit:
  • Search for failed login attempts or suspicious accesses over a given period.
• Performance analysis:
  • Extract DEBUG-level logs to measure response times or detect slow endpoints.
• User support:
  • Retrieve a user's journey (via user_id) to understand a bug or complaint.
• Automated monitoring:
  • Integrate log reading into a script or external tool to generate alerts in case of detected anomalies.
• Migration or refactoring validation:
  • Compare logs before/after a migration to ensure no regressions.