What problem does MCP, the Model Context Protocol, solve, and what should you check before plugging a third-party MCP server into your assistant?
What they are really testing: MCP went from spec to default integration layer fast, and 2026 loops ask about it. The second half is the real filter: an MCP server is third-party code and content entering your trust boundary, and treating installation as neutral is the junior tell.
A real interview question
What problem does MCP, the Model Context Protocol, solve, and what should you check before plugging a third-party MCP server into your assistant?
What most people say
drag me
“MCP is a standard for connecting LLMs to tools and data sources, it makes integrations plug-and-play so you can add capabilities quickly.”
Accurate marketing. The interviewer asked what to check before plugging one in, and "plug-and-play" without a trust analysis is precisely the behaviour that turns a helpful assistant into a data-exfiltration path.
The follow-ups they ask next
What is tool poisoning in the MCP context?
Malicious instructions embedded in a tool description or result, which the model reads as context. Defences: review and pin descriptions at install time, allowlist servers, and monitor for behaviour shifts after server updates.
Local versus remote MCP servers, what changes in the risk picture?
Local servers run code on your machine with your file system; remote ones hold credentials server-side and add a network trust hop plus an authentication story. Different failure modes, same least-privilege discipline.
What the interviewer is listening for
- Explains the N times M integration problem MCP collapses
- Treats servers as supply chain: provenance, pinning, scoped credentials
- Names tool descriptions and results as injection surfaces to review and log
What sinks the answer
- Describes benefits with no trust analysis
- Would let users self-install arbitrary servers
- Hands servers broad credentials because scoping is inconvenient
If you genuinely do not know
Say this instead of freezing. Reasoning out loud from what you do know beats silence every single time, and a good interviewer is listening for exactly that.
“MCP solves [every-assistant-times-every-tool custom integration] with [a standard protocol for exposing tools and resources]. Before installing one: [provenance and version pinning], [least-privilege scoped credentials], [review tool descriptions as an injection surface], and [log every call]. Consequential actions still [gate on a human].”
Keep going with agents & tools
Junior
How does tool calling actually work under the hood, and what makes a tool definition good versus bad?
Mid
What actually is an agent, mechanically, and what stops one from looping forever or going off the rails?
Senior
When do multi-agent architectures actually earn their complexity over one well-tooled agent, and what fails in them?
Mid
Users report your RAG assistant is giving wrong answers. Walk me through how you debug it.
Mid
What are hybrid search and reranking, and when does a RAG system actually need them?
Mid
Design the guardrails for a customer-facing AI assistant. What layers do you put around the model?
Knowing the answer is not the same as recalling it under pressure
Sign in to send the questions you fumble to spaced recall, so they come back right before you would forget them, and learn the concepts behind them with hands-on labs.
Start free