Analysis of Claude Code's ~12K Token Forced System Prompt Reveals Priority Rules Overriding User Config

An anonymous developer has extracted and annotated the ~12K token system prompt that Anthropic injects into every Claude Code turn — before any user-defined CLAUDE.md, memory files, or skills. The full annotated transcript is published at prompt.anashel.com.

Key Findings

• Song lyric prohibition: A rule stating "Never reproduce song lyrics in ANY form" is injected into every turn, even when debugging MCP tool auth in a Cloudflare worker — a universal behavioral constraint unrelated to coding tasks.
• Subagent delegation rule: In practice, Opus delegates architectural reasoning to Haiku, which then treats those conclusions as ground truth and may ignore the actual codebase.
• Three stacked 'be brief' rules: Multiple brevity directives are layered without any mechanism to detect when depth is actually warranted, potentially cutting off thorough explanations.

Annotation Structure

The annotations are color-coded by three concerns:

• Behavioral (rules shaping Claude's response style)
• Hierarchy (where the rule sits in the prompt stack)
• Scope (rules firing in contexts they were never designed for)

The author argues that this monolithic patchwork prompt, firing indiscriminately in every direction, should be replaced by a more targeted mechanism. Every Claude Code user should have visibility into what's actually running above their stack.