# Cursor tips, Claude Code errors, how to write a sy > Source: > Published: 2026-07-30 18:52:29+00:00 # Cursor tips, Claude Code errors, how to write a sy [Claude Code](/en/tags/claude%20code/)Errors – It Was My System Prompt All Along Last Tuesday afternoon, I was deep in a Django API refactor, using [Cursor](/en/tags/cursor/) with Claude Code to automate the error-handling layer. Everything looked fine — until Claude returned an empty response with this: ``` Error: Output did not conform to the required structure. Please refine your system instructions. ``` I stared at it for a solid minute. “Required structure”? My system prompt was literally “Write clean Python code. Consider edge cases.” That was it. I figured [Claude](/en/tags/claude/) would just know. Apparently, it didn’t. That error kicked off a two-day rabbit hole of Claude Code errors, Cursor settings, and a painful lesson in what makes a system prompt actually work. Here’s how I dug myself out. ## The Error That Stopped Me Cold My workflow: I had Cursor open in agent mode, connected to Claude Code (the CLI tool) for larger refactors. I’d write a high-level task — “Add comprehensive error handling to all API views in `views/` ” — and Claude would crunch through the files. Or so I thought. After the first failure, I tried again. Same error. Then I noticed a pattern: if I kept the system prompt extremely short (my “clean Python code” line), Claude would start strong but then choke on the next step. It would produce partial code, miss imports, or just bail out with that “output did not conform” message. The full error log showed something more specific: ``` Claude Code encountered an unrecoverable error after 4 attempts: Unable to produce valid output matching the specified schema. Falling back to user guidance. Please revise your system prompt. ``` Schema? I hadn’t defined any schema. That’s when it clicked: Claude Code (especially the agent mode) uses the system prompt to infer a structured output format. If you don’t tell it exactly *how* to return code, it tries to guess, and when the guess fails, it gives up. My prompt was asking for “clean code” but not specifying the delivery mechanism. ## Why My System Prompt Sucked I’ll admit it: I was being lazy. I assumed a modern LLM would just *know* I wanted a diff format, or a full file replacement, or a step-by-step explanation. But Claude Code is a tool that hooks into your editor — it needs explicit instructions for how to interact with files. My original prompt: *”Write clean Python code. Consider edge cases. Keep it modular.”* That’s three vague statements. No file structure, no format, no constraint on imports, no mention of existing code style. It’s like telling a contractor “build a nice house” without giving them blueprints. Of course they’d screw up. I scoured the PromptCube community’s [Prompt Sharing](/en/category/prompts/) category for inspiration. People were posting their system prompts for Claude Code with line-by-line breakdowns. That’s when I saw the light: a good system prompt isn’t just a description of the task — it’s an *interface contract*. It defines: - The role (senior Python dev, stick to project conventions) - The output format (full code blocks, diff hunks, or structured JSON) - The constraints (no third-party deps beyond what’s in `requirements.txt` ) - The error handling strategy (if reasoning fails, ask before guessing) ## Rewriting the Prompt ( [Next JusTTY: A Lightweight macOS Terminal Alternative →](/en/threads/4291/) ## All Replies （0） No replies yet — be the first!