Implementing Claude API Tool Use in Next.js: Full Code, 27 Minutes

I opened the editor at 16:42 and it was running in production at 17:09. Here's the full code for implementing Claude API tool use — 27 minutes of actual work. I expected it to be complicated. It wasn't. What I built Added a natural language interface to a SaaS admin dashboard. Type "show me last month's revenue" or "how many active users do we have?" and Claude queries the DB and returns the answer. The mechanic is simple: you tell Claude "you're allowed to call these functions." Claude decides