Section

Design

Choices you make once the loop runs: tools a model uses well, answers in a fixed shape, a workflow or an agent, long contexts, parallel work, sub-agents, and MCP.

  1. Workflow or agent? Programs that call a model come in five shapes, from a fixed sequence of calls to several cooperating agents. Pick the simplest one that handles the task, go further only when the task forces you to, and mix shapes when a task has a routine part and an open-ended part.chapters 1, 5, 6, and 13

Each design page names the problem, shows the design in Go, and says what it cost when the book measured it, with a short list of when to reach for it and when to leave it out.