Opus Prompting

name: opus-prompting description: | Writing assistant that identifies artifact type (CLAUDE.md, skill, command, agent prompt) and surfaces relevant prompt patterns when invoked. Covers Claude's behavioral properties, over-specification prevention, and agentic workflow design.

Prompt Writing Assistant

Claude follows natural language more literally than most models expect. The primary failure mode is overtriggering and over-specification — not under-compliance. Write less, trust more.

If unsure whether these behavioral properties are current, check the system date and search for the latest Claude model documentation.

Claude Behavioral Properties

Applying These Patterns

Read these artifact-type blocks to identify which patterns matter most for your current task. Pattern numbers reference references/patterns.md.

CLAUDE.md Instructions

Key concern: Over-specification compounds across every session. Each unnecessary rule burns token budget and can trigger the behaviors it's trying to prevent.

• Pattern 1 (Aggressive language) — soften or remove MUST/NEVER/CRITICAL; they cause overtriggering in instructions that persist across sessions
• Pattern 5 (Context/motivation) — one because... per constraint lets Claude generalize rather than memorize
• Pattern 6 (Over-specification) — describe intent, not exhaustive rules; three similar lines beat a premature abstraction

Guidance: Write guidelines a colleague would follow without needing to memorize them. If a rule triggers the behavior it's preventing (e.g., NEVER be verbose makes the prompt verbose), cut it.

Skill Body (SKILL.md)

Key concern: The description field in frontmatter is a token-budget signal — it controls when the skill loads into context. Lead with what the skill does when invoked, not what subject it covers.

• Pattern 7 (Verbosity) — skill descriptions are ranking signals; every word must earn its place
• Pattern 6 (Over-specification) — progressive disclosure: frontmatter triggers loading, body provides depth
• Pattern 4 (Formatting) — match the skill's prose style to the output you want from the model

Guidance: First sentence of description should be a verb phrase naming the activation behavior (e.g., "identifies X and surfaces Y" not "covers X, Y, and Z"). See also: claude-skill-creator skill.

Slash Command Template

Key concern: Command templates are read once per invocation. The model parses them linearly — structure (especially XML) matters more than in persistent context.

• Pattern 8 (XML structure) — use semantic tags (<workflow>, <reference>, <current-state>) to separate mutable from immutable sections
• Pattern 4 (Formatting) — prompt format influences output format; structure the template like you want the output
• Pattern 3 (Tool invocation) — conditional tool use (Use [tool] when...) prevents overtriggering in command workflows

Guidance: Front-load the command's purpose and exit criteria. $ARGUMENTS substitution is a command-only feature — if this content is in a skill, arguments won't route. See also: slash-command-creator skill.

Agent System Prompt

Key concern: Agents are more literal than interactive sessions. Overtriggering is amplified because agents act autonomously on every instruction.

• Pattern 1 (Aggressive language) — MUST/ALWAYS in agent prompts cause pathological tool loops
• Pattern 3 (Tool invocation) — describe tools conditionally; agents will invoke every tool that sounds relevant
• Pattern 6 (Over-specification) — agents handle novel situations better with principles than with exhaustive rules

Guidance: Describe tool use conditionally (Use X when Y) not imperatively (Always use X). Test by asking: if this instruction fires incorrectly, what's the blast radius?

Self-Check

Before outputting, run these three tests:

1. Golden rule: Would a colleague with minimal context understand this without asking clarifying questions?
2. Self-defeating instructions: Does any instruction trigger the behavior it's preventing? (MUST NOT be verbose is itself verbose; NEVER overthink invites overthinking)
3. How vs what: Am I specifying how when the reader only needs what? (If yes, cut the how — Claude will find an appropriate implementation)

References

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