Building a Personal AI Agent with Claude Code: Lessons from 6 Months of Wiz

A developer has shared their six-month journey building Wiz, a personal AI agent using Claude Code as both the development environment and runtime. The project started with an ambitious "Jarvis from Iron Man" vision but evolved into a practical daily-use system.

What Wiz Actually Does

Wiz is a personal AI agent built on Claude Code that runs autonomously for routine tasks. The system handles morning reports, evening summaries, inbox triage, and various experiments. For creative or quality-sensitive work, the developer remains in the loop.

Technical Implementation

The architecture is intentionally simple:

• Claude Code serves as the harness/framework
• CLAUDE.md contains the instructions file
• Memory lives in markdown files
• Tools are implemented as scripts in folders

Development Process with Claude Code

The developer used Claude Code extensively throughout the project:

• The /init command generated the first CLAUDE.md file in one shot
• When debugging was needed, errors were pasted back to Claude Code for diagnosis
• Claude Code wrote most of the code, with the developer reviewing each file and correcting issues

Key Mistakes and Lessons

The developer identified 9 specific mistakes that caused problems:

• Letting Claude generate the first CLAUDE.md without careful review - led to hours of debugging from a single bad sentence
• Allowing self-improvement to rewrite core instructions without guardrails - caused the system to drift in multiple directions
• Running Opus on every small query until hitting usage limits before lunch - fixed by implementing model routing (small/local for simple tasks, Sonnet for general work, Opus for complex calls)
• Trying to build "Jarvis" on day one instead of incrementally - cost approximately three months of development time
• Putting an LLM call in every step of every pipeline when most should have been plain scripts

Practical Starting Point

The developer recommends starting with a small, functional agent rather than an ambitious system. They suggest building something that reads overnight email and writes a one-paragraph morning summary as a first project.

The full post includes a step-by-step walkthrough of building a first agent and details all 9 mistakes. The developer notes that Wiz remains a personal project, not something being released publicly.