Names the domain (Gmail) and one specific action (send an email), but only describes a single capability rather than listing multiple concrete actions like composing, replying, attaching files, etc.

States what it does (send an email via Gmail) but has no 'Use when...' clause or explicit trigger guidance, which per the rubric caps completeness at 2, and the 'what' is also minimal, so this scores a 1.

Includes 'Gmail' and 'send an email' which are natural terms users would say, but misses common variations like 'compose', 'email message', 'mail', or 'write an email'.

'Gmail' provides some specificity that distinguishes it from generic email skills, but 'send an email' is broad enough that it could overlap with other email-sending skills (e.g., Outlook, SMTP-based tools).

Every section earns its place: flags table is reference-dense, examples are varied but not redundant, tips add non-obvious information (RFC 5322, 25MB limit, HTML fragment guidance). No unnecessary explanation of what email is or how MIME works.

Fully copy-paste ready CLI commands with clear flag documentation. Seven concrete examples cover common use cases (plain text, CC, HTML, alias, attachments, multiple attachments, draft). The flags table provides all needed details.

This is a single-command skill, so complex multi-step workflows aren't needed. The write-command caution with user confirmation requirement serves as the validation checkpoint. The --dry-run and --draft flags provide safety mechanisms. Clear and unambiguous.

Clean structure with prerequisite reference to shared auth/flags skill, well-organized sections (Usage → Flags → Examples → Tips → See Also), and one-level-deep references to related skills. Content is appropriately scoped to this single command.