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CCAR-F · Study Guide

← Build Exercises

Domain 2

Tool Design & MCP Integration

5 build exercises to practice the concepts in this domain.

2.1Beginner30 minutes

2.1 — Design Tool Descriptions That Eliminate Misrouting

What you will learn

  • Tool descriptions are what the model uses to pick a tool.
  • A production description states purpose, inputs, examples, edge cases, and boundaries.
  • How overlapping descriptions send the call to the wrong tool.
  • How a system prompt can override a clear description.
Open lesson 2.1
2.2Intermediate45 minutes

2.2 — Build Structured Error Responses for All Four Categories

What you will learn

  • An error payload carries errorCategory, isRetryable, and a description.
  • An access failure is isError true. A valid empty result is isError false.
  • The four categories: transient, validation, business, and permission.
  • Recovery follows the metadata: retry, fix the input, change path, or escalate.
Open lesson 2.2
2.3Intermediate45 minutes

2.3 — Configure Tool Distribution Across a Multi-Agent System

What you will learn

  • Keep about four or five tools on each role.
  • Give a role the one cross-role tool it needs so it does not bounce through the coordinator.
  • tool_choice auto, any, and a forced tool name cover different guarantees.
  • Replace a wide generic tool with a narrower one.
  • Check that one role cannot call another role's tools.
Open lesson 2.3
2.4Beginner30 minutes

2.4 — Configure MCP Servers with Scoping and Environment Variables

What you will learn

  • Project servers live in .mcp.json and travel with the repo.
  • Credentials expand from environment variables so they stay out of git.
  • User-level config is personal and is not shared by a clone.
  • Expose MCP resources so the model does not have to explore for standing data.
  • Write MCP tool descriptions that can compete with built-in tool descriptions.
Open lesson 2.4
2.5Intermediate30 minutes

2.5 — Trace and Refactor a Deprecated Function Using Built-in Tools

What you will learn

  • Grep finds content. Glob finds paths. Use them in that order.
  • Discover the codebase in steps instead of reading every file first.
  • Edit is the modification tool. Widen the anchor, or use replace_all, when the match is not unique.
  • Follow a function through wrappers and barrel files.
  • After Grep finds the callers, Glob finds their tests.
Open lesson 2.5