documenting-code-comments

Guidance for writing code that explains itself and using comments only when they add important context. It focuses on explaining why a decision exists, rather than repeating what the code already shows.

In plain words
What is it for?
Auditing comments, deciding whether new comments are useful, and documenting workarounds, edge cases, external rules, or deliberate performance choices.
Why use it?
It helps prevent cluttered or outdated comments that make code harder to maintain. It also highlights cases where a clearer name or structure is better than an explanation.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/rileyhilliard/agentrc/documenting-code-comments
Any agent
npx skills add rileyhilliard/agentrc --skill documenting-code-comments
Clone the repo
git clone --depth 1 https://github.com/rileyhilliard/agentrc

Made for: Claude Code, Codex.

Per session 30 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 524 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00030 $0.00524
Opus 5 $0.00015 $0.00262
Sonnet 5 $0.00006 $0.00105
Haiku 4.5 $0.00003 $0.00052

Measured yesterday against content hash 561935bfef3d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

documenting-code-comments scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agentrc/skills/documenting-code-comments/SKILL.md · 75 lines

What it actually says

Code Comments

Core principle: The best comment is the one you didn't need to write.

Hierarchy

  1. Make code self-documenting (naming, structure)
  2. Use type systems for contracts
  3. Add comments only for WHY, never WHAT

When NOT to Comment

Avoid Why
// Get the user's name Restates code
@param {string} email Types already document
Stale comments Misleading > missing

When TO Comment

WHY, Not WHAT

// Use exponential backoff - service rate-limits after 3 rapid failures
const backoffMs = Math.pow(2, attempts) * 1000;

Gotchas and Edge Cases

// IMPORTANT: Assumes UTC - local timezone causes date drift
const dayStart = new Date(date.setHours(0, 0, 0, 0));

External Context

// Workaround for Safari flexbox bug (JIRA-1234)
// Per RFC 7231 §6.5.4, return 404 for missing resources

Performance Decisions

// Map for O(1) lookup - benchmarked 3x faster than array.find() at n>100
const userMap = new Map(users.map(u => [u.id, u]));

Refactor Before Commenting

Instead of comment Refactor to
// Get active users const activeUsers = users.filter(u => u.isActive)
// 86400000 ms = 1 day const ONE_DAY_MS = 24 * 60 * 60 * 1000
// Handle error case Extract to handleAuthError(err)

TODO Format

// ✅ TODO(JIRA-567): Replace with batch API when available Q1 2025
// ❌ TODO: fix this later

Audit Checklist

  1. Necessity - Can code be refactored to eliminate comment?
  2. Accuracy - Does comment match current behavior?
  3. Value - Does it explain WHY, not WHAT?
  4. Actionability - TODOs have ticket references?
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 75 lines · 30 tokens per session scan A 561935bfef3d

Subscribe to this mod's changes

documenting-code-comments is a skill published in the GitHub repository rileyhilliard/agentrc (3 stars, last pushed 6mo ago), licensed MIT. It adds 30 tokens to every session and 524 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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