A 10-day crash plan for MCP and tool-calling interviews

Ten days is enough to prepare for an interview focused on MCP and tool calling if you already code comfortably and have called a model API. MCP, the Model Context Protocol, is a way to expose tools and data to models through servers that clients can connect to. The plan covers concepts, design, and failure handling and ends with rehearsal.

Day 1 is tool calling basics. Learn how a model chooses a tool, how arguments are passed as structured data, and how the result goes back into the conversation. Write a tiny loop by hand with one tool, so you understand the mechanics before any framework hides them.

Day 2 is MCP concepts. Learn the roles of clients and servers, and what a server exposes, such as tools and resources. Practice explaining why a protocol for this is useful compared with wiring every tool directly into every app. The MCP interview guide at /blog/mcp-interview-questions-guide covers the core questions.

Day 3 is building a small server. Expose two or three tools, such as searching notes, reading a file, and creating a task. Connect it to a client and watch the calls happen. Keep a log of every request and response.

Day 4 is tool design. Give each tool one clear job, a precise name, typed inputs with required fields, and a description that says when to use it and when not to. Design outputs as carefully as inputs: short and structured, with errors that tell the model whether to retry, ask the user, or stop. The composite story at /blog/bombed-agent-tool-design-round-checklist turns this into a checklist.

Day 5 is failure modes. Think through timeouts, partial failures, malformed arguments, duplicate calls, and tools that return far more data than the model needs. Add retries where they are safe and idempotency for anything that changes state. The guide at /blog/mcp-tools-servers-failure-modes-interview is the main reading for this day.

Day 6 is security. Treat tool results and server content as untrusted, because they can carry injected instructions. Check authorization inside the tool using the caller's identity, use least-privilege credentials, and require confirmation for irreversible actions. The MCP security guide at /blog/mcp-security-interview-questions covers this.

Day 7 is orchestration. Put your tools behind an agent with explicit state, step limits, and a hand-off to a human. The LangGraph and MCP deep-dive at /blog/langgraph-mcp-deep-dive and the LangGraph agent system design guide at /blog/langgraph-agent-system-design-interview-guide show how these fit together.

Day 8 is evaluation. Build a small set of tasks with the expected end state for each, and check the records the agent changed and the steps it took, not only its reply. Run each task more than once. The composite story at /blog/failed-agent-trajectory-eval-round explains why the trajectory matters.

Day 9 is system design. On paper, with a timer, design something like an assistant that can read a team's tickets and create follow-up tasks through MCP servers. Cover requirements, which servers and tools, permissions, failure paths, evaluation, and cost.

Day 10 is rehearsal. Write a five-minute story of your server and agent: what you built, what broke, how you found it, and what you changed. Do one mock out loud and rest.

The thread through all ten days is simple. Know the mechanics, design tools for a caller that makes mistakes, put security in code rather than in prompts, and judge the agent by what it actually did.