Leave Manager

Scope of Work - MCP (Model Context Protocol) Server

Project Overview

leave_manager is a Model Context Protocol (MCP) server that exposes a complete employee leave management workflow as a set of callable tools, enabling natural-language interaction with an HR system through any MCP-compatible client (demonstrated here with Claude Desktop). The project demonstrates hands-on agentic tool-use architecture, going beyond simple request/response patterns to implement a stateful, multi-step approval workflow.

Objectives

• Design and implement an MCP server using the official Python MCP SDK (FastMCP) to expose backend business logic as LLM-callable tools.
• Model a realistic two-step HR workflow (request → approval) rather than a single-step CRUD operation, requiring in-memory state management across tool calls.
• Integrate the server with Claude Desktop via claude_desktop_config.json, using uv for environment and dependency management.
• Validate end-to-end tool invocation through natural language prompts, confirming correct parameter extraction, state mutation, and error handling.

Core Features / Tools Implemented

• get_leave_balance(employee_id) — Retrieves an employee's current leave balance and leave history; handles invalid employee IDs gracefully.
• apply_leave(employee_id, leave_dates) — Submits a leave request for one or more dates; validates against available balance and creates a pending request rather than auto-approving, enabling a manager-review step.
• get_pending_requests() — Lists all outstanding leave requests awaiting manager approval, supporting the manager-facing side of the workflow.
• approve_leave(request_id) — Approves a pending request by ID, deducting the leave balance and updating history only at the point of approval (not at submission), modeling a real-world authorization gate.
• get_leaves_history(employee_id) — Returns an employee's full leave history.

Technical Implementation

• Protocol & SDK: Built using the Model Context Protocol (MCP) Python SDK (mcp[fastmcp]), exposing typed, schema-validated tools (input/output schemas auto-generated from Python type hints).
• State Management: In-memory data store with a request-ID-based pending-requests queue, separating "submission" state from "approved" state to mirror real HR approval flows.
• Environment Management: Project dependencies and execution managed via uv (pyproject.toml-based), with the server launched through uv run for reproducible environment isolation.
• Client Integration: Configured as a local stdio-based MCP server in Claude Desktop (claude_desktop_config.json), verified via Claude Desktop's MCP developer logs (tools/list, initialize, and live tool-call traces).
• Error Handling: Defensive checks for invalid employee IDs, insufficient leave balance, duplicate/invalid request IDs, and already-processed requests.

Skills Demonstrated

• Agentic AI / Tool-Calling architecture (MCP protocol, tool schema design)
• Python backend development (state machines, data validation, error handling)
• AI client integration and debugging (Claude Desktop config, MCP server logs, uv-based environment isolation)
• API/tool design principles applicable to production agentic systems (idempotency, separation of request vs. approval state)

Future Enhancements (Optional Roadmap)

• Persist data to a real database (SQLite/MongoDB) instead of in-memory storage.
• Add role-based access control (employee vs. manager permissions per tool).
• Add a reject_leave tool and notification/audit logging for approvals and rejections.
• Expose as a remote MCP server (HTTP/SSE transport) for multi-user access beyond local Claude Desktop.