documentation

Rules for writing documentation that a developer with no project background can understand and use. They call for concrete explanations, working examples, prerequisites, clear steps, and updates to existing project documents when code changes.

In plain words
What is it for?
Use them when writing or reviewing README files, specifications, module or function explanations, setup instructions, and documentation for code changes.
Why use it?
They prevent documentation from depending on insider knowledge or becoming inaccurate after the code changes.

Cursor rule for Cursor

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 rules/wiggitywhitney/mcp-commit-story/documentation
Clone the repo
git clone --depth 1 https://github.com/wiggitywhitney/mcp-commit-story

Made for: Cursor.

Per session 545 This file is loaded in full into every session.
When invoked 545 The same file — it is already loaded in full.
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 $0.00545 $0.00545
Opus 5 $0.00272 $0.00272
Sonnet 5 $0.00109 $0.00109
Haiku 4.5 $0.00055 $0.00055

Measured 2d ago against content hash b05f388ffc13, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

documentation 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 2d ago.

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.

.cursor/rules/documentation.mdc · 69 lines

How it starts

The opening of the file, as written. The whole thing — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Documentation Standards

Core Principle

Write for a future developer with zero project knowledge who needs to understand and modify this system.

Some Possible Elements

  • Function-level docstrings for all new functions following the core principle
  • Module-level docstrings for new modules explaining their purpose and approach
  • Complete examples that are copy-pasteable and work
  • Technical context explaining why decisions were made when it affects future changes
  • Prerequisites: What they need to install/know first
  • Clear steps: How to use, modify, or extend

Documentation Updates for Code Changes

  • Evaluate existing documentation before creating new files - determine if new information should be added to existing docs rather than creating separate files
  • When code is changed (as opposed to net-new), these must be evaluated and updated if needed:
    • Documentation files
    • README.md
    • Engineering specifications
    • PRD (Product Requirements Document)

Forbidden Content

  • Process references: No task IDs, sprint numbers, team workflows
  • Historical narrative: Skip "we tried X then Y" stories
  • Assumed knowledge: No insider team decisions or project history
  • Personal references: No names, meetings, or timeline details
  • Abstract corporate speak: Use concrete problem descriptions instead
  • Meaningless task references: Describe actual accomplishments, not task numbers

Writing Style Requirements

  • Specific, concrete language - avoid abstract buzzwords
  • Real problem/solution statements - not theoretical concepts
  • External reader accessibility - assume no prior project context
  • Focus on what's happening - not the development journey

Quality Test

Could a new developer use this documentation successfully without asking questions?

Examples

✅ Good

# Email Service

## Prerequisites
- Node.js 18+, environment vars: `SMTP_HOST`, `SMTP_USER`, `SMTP_PASS`

## Usage
```javascript
import { sendEmail } from './email-service';
await sendEmail('[email protected]', 'Welcome!', template);

Configuration

  • TIMEOUT=10000: 10s timeout prevents hanging on slow SMTP servers

Read the full file on GitHub · 69 lines

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. 2d ago First seen · 69 lines · 545 tokens per session scan A b05f388ffc13

Subscribe to this mod's changes

documentation is a cursor rule published in the GitHub repository wiggitywhitney/mcp-commit-story (15 stars, last pushed 1y ago), licensed MIT. It adds 545 tokens to every session, about $0.0027 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 2026-08-30.