Conciseness

The body is lean and assumes Claude's competence: no concept explanations, no padding, every section instructs. It is not level 5 because the Rules section partially restates the workflow ("Add new fields as optional first, migrate, then require" duplicates workflow steps 1 and 4), leaving minor redundancy that could be trimmed.

Actionability

The strategy is concrete (optional first, backfill, then require) and names the package, but there is no executable code or command anywhere: no install command, no migration function example, no run command, and no concrete verification command. This matches the anchor for some concrete guidance that is incomplete with missing key details; it exceeds level 2 because the ordering and package choice are specific, not just high-level hints.

Workflow Clarity

A clear four-step sequence with validation checkpoints present ("Run the migration; verify all rows are valid", "Verify row counts before and after", and the never-tighten-early rule). Validation steps exist, so the destructive/batch cap of 3 does not apply, but there is no explicit error-recovery feedback loop (what to do when verification fails) and verification lacks a concrete command, keeping it below level 5.

Progressive Disclosure

The skill is under 50 lines, has no external bundle files, and needs none at this size; sections are well-organized (overview, Workflow, Rules). Per the guidelines, this qualifies for a top score with just well-organized sections.

Specificity

"Migrate schema + backfill data" names the domain (Convex schema migration) and two concrete actions plus the tool "@convex-dev/migrations" and the "deployed" context. This matches the anchor for 1-2 concrete actions that is not comprehensive; it lists fewer actions than the level-4 example's several specific actions and has no vague filler that would push it below.

Completeness

The description has a clear "what" (migrate schema and backfill data using @convex-dev/migrations on a deployed app) but no "Use when..." clause or equivalent explicit trigger guidance, capping completeness at 3 per the judging guidelines. It is not level 2 because the "what" is specific rather than vague; the "when" is only weakly implied by "deployed".

Trigger Term Quality

"migrate", "schema", "backfill data", and "Convex" are precisely the natural terms a Convex user would say when needing this skill, comparable to the level-4 example's coverage. It falls short of level 5 because common variations like "production", "live database", or "schema migration" phrasing are absent.

Distinctiveness Conflict Risk

"Convex" and the exact package "@convex-dev/migrations" give this a clear niche with distinct triggers and minimal conflict risk with other skills. No other common skill domain would claim these terms.