MCP, Protocols & Multi-Agent Questions
Nine questions on MCP, tool registries and versioning, and when multiple agents are justified.
MCP is a shared plug for connecting AI to tools. Multi-agent means several agents working together. Interviewers listen for two things: that you know MCP does not make tools safe, and that you only use several agents for a clear, measurable reason.
- MCP
- A standard way to connect AI apps to tools.
- Supervisor
- The agent that hands out work to others.
- Hand-off
- Passing work and information to another agent.
- A shared plug for connecting AI to tools
- It does not make a tool safe
- Several agents working together
- Use it only for a clear, measurable reason
Protocol and multi-agent questions test whether you can separate interoperability from intelligence, and whether you're skeptical of complexity. Expect follow-ups on security and on how you'd decide between a single agent and several.
How to approach these questions
- Describe MCP as an interoperability layer for capabilities, not as the agent's brain.
- Always raise authentication, authorization, input validation and supply-chain risk for tool servers.
- For multi-agent designs, argue from context, permissions and measured benefit — never from org-chart analogies.
Q1What problem does MCP solve?show answer
In plain words: Without a standard, every app needs a custom link to every tool. MCP gives one shared way, so a tool can be reused. It does not make tools safe.
Full answer · Without a standard, connecting N AI applications to M tools or data sources means N×M bespoke integrations, each with its own discovery, auth and error handling. MCP standardizes how a host application's client discovers and calls capabilities exposed by servers (tools, resources, prompts), so a capability built once can be reused by any compatible client. It standardizes the interface, not trust, so each server remains a security boundary.
Q2What is the difference between a protocol and an agent framework?show answer
In plain words: A protocol is the rules for talking. A framework is a toolkit for building. You can use one without the other.
Full answer · A protocol defines how components talk — message formats, discovery, lifecycle — so independent implementations interoperate. A framework is a library that helps you build the agent's internals: state, graphs, memory, tracing and model integration. You can use a protocol with or without a framework, and your architecture shouldn't depend on one framework's abstractions.
Q3How would you secure an MCP server?show answer
In plain words: Check who is calling. Check permissions for each tool. Keep secrets inside the server and log everything. Give it the smallest access it needs.
Full answer · Authenticate callers (OAuth for remote servers), authorize per tool and per tenant, validate every argument server-side, limit scope and rate, keep secrets in the server (never in prompts), log every call for audit, run with least-privilege credentials and in a sandbox where it executes code, and bound response sizes. On the client side, vet and pin servers, review tool-description changes, and don't connect an untrusted server to an agent that holds sensitive data without approval gates.
Q4How should tools be versioned?show answer
In plain words: Version them like any software interface and keep old versions for a while. Test description changes, because the AI reads them.
Full answer · Like APIs: semantic versions with schemas, backward-compatible changes within a major version, deprecation windows, and a registry recording owner, version and status. Because models read tool descriptions, treat description changes as behavior changes — evaluate them. Keep old versions available until clients and prompts have migrated, and monitor tool-selection errors after a release.
Q5How would you handle capability discovery with hundreds of tools?show answer
In plain words: Do not show every tool to the AI. Keep a catalogue, show only relevant ones and still check permission when it runs.
Full answer · Don't put every tool definition in every context. Keep a registry with metadata (owner, version, risk tier, tenants, health), let the agent or router retrieve a small relevant set by semantic, categorical or policy-driven discovery, and then enforce final authorization at execution. Discovery is not permission: the registry may say a user could use a tool, but the execution layer decides. Measure tool-selection accuracy.
Q6When is a multi-agent system justified?show answer
In plain words: When agents need different information, different permissions or can do independent work in parallel, and it is measurably better.
Full answer · When the responsibilities truly need different contexts (to avoid a bloated shared window), different permissions (privilege separation, such as an agent that reads untrusted content having no write tools), parallelism over independent work, or independent verification. Otherwise one agent plus deterministic tools is simpler and cheaper. Justify each agent with a measured improvement over the single-agent baseline.
Q7How do agents hand work to each other safely?show answer
In plain words: Pass a clear package: the goal, facts, decisions, what was tried and the answer format. Check it when it is handed over.
Full answer · Through explicit contracts: the verbatim goal, the task and definition of done, verified facts with sources, decisions already made, what's been tried, artifact references instead of large payloads, and a required return schema — validated at the boundary. Add task and correlation IDs for tracing, bound delegation depth and total work, and treat each agent's output as untrusted input to the next.
Q8What are the main failure modes of multi-agent systems?show answer
In plain words: They lose information between agents, loop forever, stop too early or trust each other's mistakes. Limits and independent checks help.
Full answer · Specification problems (ambiguous roles or tasks), coordination problems (context lost at hand-offs, ping-pong loops, duplicated or conflicting work, runaway spawning) and verification problems (premature termination, cascading hallucination where one agent's invention becomes another's fact). Mitigate with explicit hand-off schemas, hard budgets, termination criteria checked outside the producing agent, independent verification and honest partial results.
Q9A and B are both agents. Should they talk directly or through a supervisor?show answer
In plain words: Use a supervisor who controls who does what. Free chatting between agents is hard to limit, test and secure.
Full answer · Prefer a supervisor that owns delegation, policy and the shared state, with specialists doing bounded tasks. Uncontrolled agent-to-agent chatter is hard to bound, debug and secure. Direct peer hand-offs can make sense in conversational flows where the user talks to whichever specialist is in charge, but then pass state explicitly and forbid immediate hand-back loops.
- ✓MCP = interoperability for capabilities; security, identity and policy are still yours.
- ✓Discovery isn't authorization; version tools and measure tool selection.
- ✓Justify each agent with context, permissions, parallelism or verification — and a measured gain.
- ✓Hand-offs need schemas, IDs, budgets and validation.
Protocol and multi-agent drill
- Explain MCP to a non-AI backend engineer in 60 seconds using an analogy you actually believe.
- List the controls you'd require before connecting a third-party tool server to an agent with customer data.
- Take a three-agent design you've seen and argue it down to the minimum number of agents.
- Write the hand-off schema for one of the agent pairs.