I'd been using Claude Code daily for months and couldn't tell if I was actually improving or just executing the same five moves faster. Asking Claude to write code, check my work, explain something — rinse, repeat. No visibility into what I wasn't doing.
In February 2026, Anthropic published a study of 9,830 Claude conversations measuring 11 observable collaboration behaviors. I wanted to see what mine looked like against that baseline, and specifically which behaviors I never touched. So I built skill-tree.
The tool analyzes your Claude Code or Cowork session history, classifies all 11 behaviors from Anthropic's AI Fluency Index against your actual messages, and assigns one of seven archetype cards — rendered as tarot cards using curated museum art. The live fixture at skill-tree-ai.fly.dev/fixture/illuminator shows what the output looks like.
The part I find most useful is the growth quest. It doesn't pick a behavior you're already doing well and suggest doing more of it. It finds a behavior you've been avoiding entirely and surfaces that as your focus for the next session. The logic is anti-local-optimum: if you're already strong at delegation (handing off tasks to Claude with minimal back-and-forth), reinforcing that doesn't expand your range. The gap behaviors — the ones where your count is zero or near-zero — are where real fluency growth lives. The quest persists across sessions via a SessionStart hook so it's waiting for you when you open the next one.
The classification taxonomy comes from Dakan & Feller's 4D AI Fluency Framework: Description, Discernment, Delegation, and Diligence (Diligence isn't visible in chat logs, so only three axes are scored). The remote classifier runs on Fly.io using Claude Haiku, returns a stable URL per analysis, and the whole 7-step orchestration — find session files, extract messages, classify, assign archetype, synthesize narrative, render, return URL — takes 30–60 seconds.
Install in Claude Code:
claude plugin marketplace add robertnowell/ai-fluency-skill-cards
claude plugin install skill-tree-ai@ai-fluency-skill-cards
Also works in Cowork via skill-tree-ai.zip, and as an MCP server (npm install skill-tree-ai) for Cursor, VS Code, or Windsurf.
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