Question 1

How do you choose the right model for a task?

Accepted Answer

**Target Audience:** Engineers adding their first LLM feature who see a long list of models and want a repeatable way to pick one.
**Difficulty:** Easy
**Verified with:** Node 22.22.0 and Python 3.12.3 (the selection harness below; the models in it are deterministic stubs and the prices are illustrative). Product and paper facts are cited inline with the date they were checked (October 2026).

> **How to read this doc:** Every idea is explained in plain language first, then tagged with `📌 Inter

Question 2

What is the Model Context Protocol (MCP) and what problem does it solve?

Accepted Answer

**Target Audience:** Engineers who have used tool calling and keep hearing "just ship an MCP server", and anyone preparing for an AI engineering interview.
**Difficulty:** Medium
**Verified with:** Node 22.22.0 and Python 3.12.3 (both examples, identical output). Protocol details were checked in October 2026 against the published SDK packages themselves: `@modelcontextprotocol/sdk` 1.32.1 (the v1 line, spec up to 2025-11-25), `@modelcontextprotocol/server` and `@modelcontextprotocol/core` 2.3.1

Question 3

How do multimodal models handle images, audio and other non-text inputs?

Accepted Answer

**Target Audience:** Engineers who have used text-only LLM APIs and now need to send screenshots, scans, photos or audio.
**Difficulty:** Medium
**Verified with:** Node 22.22.0 and Python 3.12.3 (the patch-projection demo and the token estimators below; no real model is called). Provider token rules and paper details are cited inline with the source and the date checked (October 2026).

> **How to read this doc:** Every idea is explained in plain language first, then tagged with `📌 Interview te

Question 4

Cost optimization for LLM apps: how do you keep the bill predictable?

Accepted Answer

**Target Audience:** Engineers and tech leads who already know roughly what their LLM features cost, but whose monthly bill keeps surprising finance, and who need it to land within a known range.
**Difficulty:** Medium
**Verified with:** Node 22.22.0 and Python 3.12.3 (a 30-day spend simulation with and without controls, and a worst-case and reserved-capacity calculator). All prices and traffic in the examples are **hypothetical**; provider budget and capacity features are quoted from the Anthro

Question 5

How do you choose between open-weight models and proprietary API models?

Accepted Answer

**Target Audience:** Engineers and tech leads who have shipped on a model API and are asked "should we run our own model?"
**Difficulty:** Medium
**Verified with:** Node 22.22.0 and Python 3.12.3 (the break-even model below; every input is a labelled assumption, not a quote). Licence and product facts are cited inline with the source and the date checked (October 2026).

> **How to read this doc:** Every idea is explained in plain language first, then tagged with `📌 Interview term:` so you also

AI ENGINEERINGDECODED.

Easy

How do you choose the right model for a task?

Medium

What is the Model Context Protocol (MCP) and what problem does it solve?

How do multimodal models handle images, audio and other non-text inputs?

Cost optimization for LLM apps: how do you keep the bill predictable?

How do you choose between open-weight models and proprietary API models?