Introduction: Extending Claude Code
Claude Code gives developers a programmable interface to Claude’s language model. It lets you embed model calls inside ordinary code, combine them with external tools, and orchestrate complex workflows. As applications move from single‑turn prompts to multi‑step pipelines, the need for reusable, predictable primitives grows. Engineers must decide whether to wrap tool calls in deterministic hooks, package reusable instructions as skills, or spin out parallel agents as subagents. The choice determines how easy the system is to test, how much latency it adds, and how well it scales across workloads.
Hooks are the most granular primitive. They let you run deterministic code before and after any tool call, giving you fine‑grained control over the model’s execution flow.
Hooks let you run deterministic code before and after any tool call, giving you fine‑grained control over the model’s execution flow, as described in the Anthropic Blog – Introducing Hooks for Claude Code Anthropic Blog – Introducing Hooks for Claude Code.
This level of control is useful when you need to enforce input validation, inject context, or log results without modifying the model prompt itself. Because hooks execute in the same process as the tool call, they avoid the need for separate prompt engineering steps.
