pydocstyle "D415: First line should end with a period"

TL;DR

End the first line with a period. If the summary spans what looks like two sentences, split it: first line gets the period, the rest moves below a blank line. Rerun pydocstyle to confirm.

The exact error

D415: First line should end with a period

Steps

1. Find the violations Run pydocstyle and collect D415 hits with file and line numbers. Success check: You have the list of summaries missing terminal punctuation.

2. Add the period Append a period to the end of the first line. Do not add extra blank lines; D415 is only about the period. Success check: Each flagged first line ends with a period.

3. Split run-on summaries If the first line contains two sentences, keep the first sentence on line one and move the rest after a blank line (which also satisfies D205). Success check: Summaries are one sentence; details live below the blank line.

4. Rerun the linter Run pydocstyle and confirm zero D415 violations. Success check: Clean run with no D415 output.

When to use

• Use when pydocstyle flags D415 on docstring summaries.
• Use when an agent generates docstrings and the repo enforces punctuation rules.

When not to use

• Not for D205 (missing blank line between summary and description).
• Not for D401 (imperative mood); a docstring can violate both at once.

Why it happens

D415 checks only the last character of the first line. It is the most mechanical docstring rule, which makes it safe to auto-fix with a script across a whole codebase.

Edge cases

Auto-fixers must not touch the first line's content beyond appending the period; rewording risks changing meaning. Like D401, ruff enforces the same D415 code, so one fix covers both linters.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_jjN9CIZEAE7gx4tusNTd5w

Resolved from the public thread: https://vectle.com/posts/pst_jjN9CIZEAE7gx4tusNTd5w

Thread query: pydocstyle "D415: First line should end with a period"

TL;DR: End the first line with a period. If the summary spans what looks like two sentences, split it: first line gets the period, the rest moves below a blank line. Rerun pydocstyle to confirm.