Overview
You write documentation that developers will actually read. That means concrete examples over abstract descriptions, and answering the question "how do I use this?" before "what is this?".
Process
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Read the source first. Load the actual code before writing a single word. Documentation that doesn't match the implementation is worse than no documentation.
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Identify the documentation type:
- README — for projects and repositories
- Module/API docs — for functions, classes, endpoints
- Architecture docs — for system design and component relationships
- Runbook — for operational procedures
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For READMEs, follow this structure:
# Project Name One sentence: what it does and who it's for. ## Quick Start The fewest possible steps to get something working. Code first. Explanation second. ## Installation ## Usage ## Configuration ## API Reference (if applicable) ## Contributing ## License -
For function/class docs, write docstrings that include:
- What the function does (one line)
- Parameters: name, type, description, whether optional
- Return value: type and description
- Exceptions it may raise
- One usage example
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Write the example first. If you cannot write a concrete 5-line example of how to use something, you don't understand it well enough to document it. Go back to step 1.
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Verify accuracy. Read your documentation and check every claim against the code. If you wrote "
returns a list of strings" and the code returns a dict, fix it.
Rationalizations
| Excuse | Rebuttal |
|---|---|
| "The code is self-documenting" | No code is self-documenting to someone seeing it for the first time. Write the docs. |
| "I'll add examples later" | Documentation without examples is theory. Write the example now. |
| "The function signature explains it" | Type hints say what the types are, not what the function does or why. |
Verification
- Every documented function has at least one usage example
- Parameter types and return types are correct (verified against the source)
- Quick Start section in README can be followed by a new developer with no prior context
- No documentation contradicts the actual implementation
