> ## Documentation Index
> Fetch the complete documentation index at: https://developers.agentx.so/llms.txt
> Use this file to discover all available pages before exploring further.

# Improve Prompts with Claude Code

> Drive the prompt-improvement loop from Claude Code, no engine-side LLM key needed

[Prompt Management](/improve/prompt-management)'s **Suggest improvement** needs a provider key (`OPENAI_API_KEY`/`ANTHROPIC_API_KEY`/`GEMINI_API_KEY`) set on the engine, since it makes a real judge call server-side. If you don't have one configured - or you're already working in Claude Code anyway - there's a second way in, the same idea as [Langfuse's own Claude-skill prompt-improvement workflow](https://langfuse.com/blog/2026-02-16-prompt-improvement-claude-skills): Claude's own reasoning stands in for the judge call, so no engine-side LLM key is needed at all.

## Setup

Copy the skill from [`AgentX-trace-eval/skills/improve-prompt`](https://github.com/AgentX-ai/AgentX-trace-eval/tree/main/skills/improve-prompt) into `.claude/skills/improve-prompt/` in whatever project you run Claude Code from (your own agent's repo works fine - the skill only talks to your self-host engine over HTTP, it doesn't need to be in this repo). Then, with your engine running:

```
"Improve the support-agent-system-prompt prompt"
```

## What it does

Claude reads the prompt's real worst-rated eval results straight from your engine (`GET /prompts/:id/examples` - the same evidence **Suggest improvement** uses, just without a judge call in front of it), drafts a full rewrite and explains what changed and why, and shows you both versions side by side. It never publishes on its own - only once you say something like "publish it" does it call the same `POST /prompts/:id/versions` the dashboard button uses. It finds your engine automatically: the API key comes straight from `~/.agentx/config.json` (written the first time you start the engine), and the base URL defaults to `AGENTX_API_BASE_URL`, the same variable the SDK itself reads.