Technical Writing Skill

Good documentation is the difference between a project that scales and one that stalls. Write for the reader who has zero context.

1. When to Apply This Skill

Trigger conditions:

• Writing or updating a README
• Creating API documentation
• Writing architecture decision records (ADRs)
• Building runbooks or incident playbooks
• Creating onboarding/developer guides
• Reviewing documentation for clarity

2. Document Types and Templates

Document Provenance Frontmatter

All descriptive Markdown docs must follow .github/instructions/document-frontmatter.instructions.md.

• New docs: include Original Author, Creation Date, and Creating Model in YAML frontmatter.
• Updated docs: preserve those original fields and add or update Last Author, Last Updated, and Last Model Used.
• Use full ISO 8601 UTC timestamps for Creation Date and Last Updated values.
• Merge these fields into existing frontmatter instead of replacing document-specific metadata.

README Structure

Every project README follows this order:

# Project Name
One-sentence description of what this does and who it's for.

## Quick Start
Minimum steps to run the project locally (≤5 commands).

## Prerequisites
- Runtime versions (Python 3.12+, Node 22+)
- Required tools (Docker, pnpm)
- Required accounts/access

## Installation
Step-by-step setup with copy-pasteable commands.

## Usage
Common tasks with examples.

## Architecture
Brief overview with a diagram (link to detailed docs).

## Contributing
How to submit changes, run tests, and follow conventions.

## License

Rules:

• Quick Start must work on a fresh machine in under 5 minutes
• Every command must be copy-pasteable (no <placeholder> without explanation)
• Test the README by following it literally on a clean environment

Architecture Decision Record (ADR)

# ADR-{NNN}: {Decision Title}

## Status
Accepted | Superseded by ADR-{NNN} | Deprecated

## Context
What problem are we solving? What constraints exist?

## Decision
What did we decide and why?

## Alternatives Considered
| Option | Pros | Cons | Why Not |
|--------|------|------|---------|

## Consequences
What changes as a result? What new constraints are introduced?

Runbook/Playbook

# Runbook: {Incident Type}

## Symptoms
What does the user/monitor see?

## Impact
Who is affected? What's the blast radius?

## Diagnosis Steps
1. Check {metric/log/dashboard} — expected: {value}
2. Run `{command}` — look for {pattern}
3. ...

## Resolution Steps
1. {Step with exact command}
2. {Verification step}
3. ...

## Escalation
If not resolved in {time}, contact {team/person}.

## Post-Incident
- [ ] Update this runbook with new learnings
- [ ] File ticket for permanent fix

3. Writing Principles

Know Your Reader

Reader	Needs	Writing Style
New developer	Setup, concepts, where things are	Step-by-step, no assumptions
Experienced dev	API reference, edge cases, configuration	Concise, scannable, tables
Ops/SRE	Runbooks, monitoring, deployment	Commands, checklists, decision trees
Stakeholder	What it does, status, decisions	High-level, diagrams, outcomes

The Inverted Pyramid

Put the most important information first. Readers scan, they don't read.

┌─────────────────────────┐
│    What + Why (lead)    │  ← First paragraph answers the key question
├─────────────────────────┤
│  How (details)          │  ← Supporting details, steps, configuration
├─────────────────────────┤
│  Reference (appendix)   │  ← Edge cases, history, alternatives
└─────────────────────────┘

Plain Language Rules

Do	Don't
"This function returns the user's name"	"This function facilitates the retrieval of the nomenclature associated with the user entity"
"Run npm install"	"Execute the package installation command"
"Fails if the file doesn't exist"	"In the event that the specified file is not present in the filesystem, the operation will not succeed"
Short sentences (< 25 words)	Run-on sentences with multiple clauses
Active voice	Passive voice

4. Code Examples in Documentation

Rules for Code Samples

# ✅ GOOD: Complete, runnable example with imports
from datetime import datetime
from myapp.models import User

def create_user(name: str, email: str) -> User:
    """Create a user and return the saved instance."""
    user = User(name=name, email=email, created_at=datetime.now())
    user.save()
    return user

# Usage
user = create_user("Alice", "alice@example.com")
print(user.id)  # => "usr_abc123"

# ❌ BAD: Incomplete snippet, no context
def create_user(name, email):
    user = User(name=name, email=email)  # What is User? Where is it imported?
    user.save()  # Does this return something?

Rules:

• Include imports
• Show expected output in comments
• Use realistic data (not "foo", "bar", "test")
• Every example must be copy-pasteable and runnable

5. Diagrams

Use diagrams for architecture, data flow, and sequences. Text alone fails for spatial relationships.

When to Use Each Type

Diagram	Use For
Flowchart	Decision trees, process flows
Sequence	API call chains, auth flows
Architecture	System overview, service boundaries
ERD	Database schema relationships
State	Lifecycle transitions (order, ticket)

Diagram Rules

• Label every arrow (what data flows, what triggers the transition)
• Include a legend if using color coding
• Keep to 7±2 elements — decompose larger diagrams
• Store diagrams as code (Mermaid, PlantUML) for version control

6. API Documentation

Endpoint Documentation Template

### `POST /api/v1/customers`

Create a new customer record.

**Auth:** Bearer token required

**Request Body:**
| Field | Type | Required | Description |
|-------|------|----------|-------------|
| name | string | Yes | Customer full name (1-200 chars) |
| email | string | Yes | Valid email address |

**Response:** `201 Created`
```json
{
  "data": { "id": "cust_abc", "name": "Alice", "email": "alice@example.com" }
}

Errors:

Code	When
400	Missing required field
409	Email already exists
422	Invalid email format

## 7. Documentation Maintenance

### Keep Docs Near Code

src/
auth/
login.py
README.md ← Auth module docs live with auth code
docs/
architecture.md ← System-level docs in docs/
runbooks/ ← Operational docs

### Freshness Rules

| Trigger | Action |
|---------|--------|
| API endpoint changed | Update API docs in same PR |
| New environment variable | Update README + .env.example |
| Architecture decision | Write or update ADR |
| Production incident | Update or create runbook |
| New developer onboarded | Test README, fix gaps found |

## 8. Review Checklist

When reviewing documentation:

- [ ] Answers "what does this do?" in the first paragraph
- [ ] Document frontmatter is present and current
- [ ] Code examples are complete and runnable
- [ ] Commands are copy-pasteable
- [ ] No stale references to old code, endpoints, or config
- [ ] Diagrams are up to date
- [ ] Written for the target audience (not the author)
- [ ] No jargon without definition
- [ ] Links work and point to current resources

## 9. Anti-Patterns

| Anti-Pattern | Problem | Fix |
|---|---|---|
| Docs written once, never updated | Stale docs are worse than no docs | Update in same PR as code changes |
| Wall of text | Nobody reads it | Use headings, tables, code blocks, diagrams |
| Documenting obvious code | Noise, maintenance burden | Document "why", not "what" |
| Screenshots of terminal output | Can't copy-paste, hard to update | Use code blocks with text output |
| "See the code for details" | Reader has to reverse-engineer | Write the explanation |
| Assuming reader context | "Just run the usual setup" | Spell out every step |