By default, Claude generates its response token by token without any deliberate planning step. For most tasks — answering a question, writing a function, explaining a concept — this is fine. The response comes quickly and it is good. For some tasks, it is not enough. Complex multi-step reasoning problems, ambiguous architecture decisions, intricate security analyses — these benefit from Claude thinking through the problem before committing to an answer. That is what extended thinking and adaptive thinking provide.

Building an AI agent that runs autonomously — browses the web, executes code, reads and writes files, persists memory across sessions — requires infrastructure. You need a sandbox, a process that can run for hours without your web server timing out, and a way to resume from where you left off after a network hiccup. Claude Managed Agents, launched in public beta in April 2026, offloads all of that to Anthropic.

If you are calling the Claude API repeatedly with a large system prompt, a big document, or a long codebase context — and you are not using prompt caching — you are paying full price every time for content that has not changed. Prompt caching stores a prefix of your prompt server-side and charges 90% less to read it back on every subsequent request. For applications that repeatedly process the same context, this is the single highest-impact API optimisation available.