TL;DR - 5 Bullet Summary

1. Simple Loop: Claude Code runs a while(tool_call) loop, with no DAGs, no classifiers, no RAG. The model decides everything.

2. Eight Core Tools: Bash (universal adapter), Read, Edit, Write, Grep, Glob, Task (sub-agents), TodoWrite. That's the entire arsenal.

   Search Strategy Evolution: Early Claude Code versions experimented with RAG using Voyage embeddings for semantic code search. Anthropic switched to grep-based (ripgrep) agentic search after internal benchmarks showed superior performance with lower operational complexity: no index sync required, no security liabilities from external embedding providers. This "Search, Don't Index" philosophy trades latency/tokens for simplicity/security. Community plugins (ast-grep for AST patterns) and MCP servers (Serena for symbols, grepai for RAG) available for specialized needs.

   Source: Latent Space podcast (May 2025), ast-grep documentation

3. 200K Token Budget: Context window shared between system prompt, history, tool results, and response buffer. Auto-compacts at ~75-92% capacity.

4. Sub-agents = Isolation: The Task tool spawns sub-agents with their own context. They cannot spawn more sub-agents (depth=1). Only their summary returns.

5. Philosophy: "Less scaffolding, more model." Trust Claude's reasoning instead of building complex orchestration systems around it.