# 4. The Self-Checking Build

A long run that drifts off spec in hour one wastes everything after it. Fable 5 can catch this itself, but only if you ask.

**When to use:** Add to any long-running job: a build, a big document, a research project, a batch of pages.

## The prompt

```
Establish a method for checking your own work at an interval of [every major step / every 30 minutes / every section] as you build. Run this check every interval, verifying your work with subagents against the specification. If a check fails, fix it before moving on.
```

**Why it works:** Anthropic found that fresh-context checkers outperform the model critiquing itself, like a builder who stops every hour to check the level.

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Adapted from Anthropic's official Claude Fable 5 prompting guide.
Full guide with all 12 prompts: https://www.waboom.ai/resources/claude-fable-5