# Body Discipline Reference

Source: agentskills.io — skill-authoring

## The core test

For every sentence in the body, ask: **"Would the agent get this wrong without this instruction?"**

If no — cut it. The agent already knows it from general training. Adding it wastes tokens and dilutes the signal of what matters.

## What belongs in the body

Include content the agent lacks:
- Project-specific conventions and domain procedures it cannot infer
- Non-obvious edge cases and environment-specific gotchas
- The specific tools or sequences to use (not the full range of options)
- One default per decision point with one escape hatch

Do not include:
- Concepts the agent already knows (what JSON is, how HTTP works, what a CSV is)
- Exhaustive option lists — pick a default; the agent doesn't benefit from choosing
- Steps the agent handles independently — over-specifying leads to unproductive paths
- Restatements of the description — it's already in context

## Calibrating control

**Be prescriptive** when operations are fragile, consistency matters, or a specific sequence must be followed:
```markdown
Run exactly:
\`\`\`bash
python scripts/migrate.py --verify --backup
\`\`\`
Do not modify the command or add additional flags.
```

**Give freedom** when multiple approaches are valid. Explaining *why* outperforms rigid directives — agents make better decisions when they understand the purpose.

## Defaults not menus

Never present a list of equivalent options — pick one and mention the alternative briefly:
```markdown
# Too many options
Use pypdf, pdfplumber, PyMuPDF, or pdf2image...

# Default with escape hatch
Use pdfplumber for text extraction. For scanned PDFs requiring OCR, use pdf2image instead.
```

## Gotchas sections

Highest value content — environment-specific facts that defy reasonable assumptions. Place near the top of the body so the agent reads them before encountering the situation.

```markdown
## Gotchas
- The `users` table uses soft deletes. Always include `WHERE deleted_at IS NULL`.
- User ID is `user_id` in the database, `uid` in auth, `accountId` in billing. Same value.
```

Each entry must be a specific, surprising fact — not a general tip or reminder.

## Progressive disclosure

Keep `SKILL.md` under 500 lines. When more content is needed, move it to `references/` and load conditionally:

```markdown
If the API returns a non-200 status, read `references/api-errors.md`.
```

"If X, read Y" is more useful than "see references/ for details." The agent loads on demand rather than up front.

## Auditing guidance

Flag as FAIL if:
- A sentence answers "no" to the core test (would agent get this wrong without it?) — it is padding
- Decision points present a menu of options with no default
- Instructions repeat content already in the description
- Prescriptive sequences are used where flexibility is fine, or vice versa

Flag as SUGGESTION if:
- A rationale is missing from an include/exclude rule (present but unexplained)
- Gotchas are correct but placed late in the body rather than near the top
- A conditional reference trigger is vague ("see references/") rather than specific ("If X, read Y")