QABattle

Agentic AI Testing / Scenario

The MCP Server Contract Break

An MCP server update broke every agent connected to it. Read the tool definitions, the agent errors, and the change, then diagnose the contract violation.

Difficulty
Hard
Format
Scenario
Points
200
Estimate
15 min

// MISSION BRIEF

Your Mission

The Model Context Protocol (MCP) lets agents discover and call tools from a server. Your team ships an MCP server that three agent apps depend on. After a "small improvement", all three started failing.

You have the before/after tool schema, the agent-side error, and a sample call. MCP tool schemas are contracts, find the break.

// FIRST CONTACT

Battle teaser

First artifact

MCP tool definition, before vs after

Which changes broke the contract? (Select all that apply.)

  1. ARenaming query → searchQuery
  2. BAdding the optional filters object
  3. CMaking limit required (was optional with a default)
  4. DRemoving the default value from limit
Answers, scoring, hints, and the full battle stay sealed.

// SKILL TAGS

mcpcontractsagentsbreaking-changes