Commenting Code

Code Commenting Rules

Decision Rule

If information can be extracted from code (function name, parameters, types, return type), the comment is USELESS. If it explains WHY, documents for non-developers (UI), or warns about non-obvious behavior, KEEP IT.

❌ REMOVE - Useless Comments

1. Visual Separator Comments

# =============================================================================
# Section Name
# =============================================================================

Noise. Code structure should be self-evident from organization.

2. Single-line Docstrings Repeating Signature

def enable(self, user: str | None = None) -> None:
    """Enable this ingestor configuration."""  # REMOVE

def get(self, config_id: UUID) -> IngestorConfig | None:
    """Get an ingestor config by its ID."""  # REMOVE

def delete(self, config_id: UUID) -> bool:
    """Delete an ingestor config by ID. Returns True if deleted."""  # REMOVE

Function name + parameters + return type already tell the story.

3. Comments Stating WHAT Code Does

# Loop through items  # REMOVE
for item in items:
    process(item)

Code already shows this.

✅ KEEP - Useful Comments

1. Django help_text on Model Fields

enabled = models.BooleanField(
    help_text="Whether this ingestor is active"  # KEEP
)

UI documentation for admin users, not developer comments. Serves runtime purpose.

2. Contract/Interface Documentation

class IngestorConfigRepository(ABC):
    """
    Repository interface for IngestorConfig persistence.

    Returns Django models directly (no mapping layer).
    """  # KEEP

Guides implementers. Documents design decisions and constraints.

3. WHY Explanations

# Minimum 60s to avoid API rate limiting  # KEEP
if poll_interval_seconds < 60:
    raise ValueError(...)

Intent not obvious from code alone.

4. Side Effects / Warnings

def update_cursor(self, new_cursor: str | None) -> None:
    # Also resets error_count and last_error_message  # KEEP

Non-obvious behavior that callers should know.

5. Business Rules

# Health thresholds: 0 = healthy, 1-4 = warning, 5+ = failing  # KEEP

Domain knowledge not evident from code.

6. Multi-line Class Docstrings with Value

class IngestorService:
    """
    Orchestrates ingestor execution.

    Responsibilities:
    - Execute ingestion cycles (polling mode)
    - Test external connections
    - Track run history and metrics
    """  # KEEP - explains purpose and responsibilities

7. NOTE/WARNING Comments

# NOTE: This admin is NOT registered by default.
# Raw events have short retention (14 days).  # KEEP

Important warnings for developers.

Quick Test

Before writing or reviewing a comment, ask:

1. Can I get this info from the function signature? → REMOVE
2. Does it explain WHY, not WHAT? → KEEP
3. Is it for end users (help_text, admin UI)? → KEEP
4. Does it warn about non-obvious behavior? → KEEP
5. Is it just visual decoration? → REMOVE

Usage

This skill activates when:

• Reviewing code comments for quality
• Cleaning up docstrings
• Checking if comments add value
• Refactoring code documentation

Apply these rules to identify and remove useless comments while preserving meaningful documentation.