Conciseness

The body is mostly lean — the schema-validation constraint, the widen-migrate-narrow pattern, and the pitfalls are Convex-specific knowledge Claude would not already have. A few sentences drift toward over-explanation ("This is the fundamental constraint that shapes every migration", "This makes the transition safer and easier to roll back"), landing it on anchor 4 rather than anchor 5's 'every token earns its place'.

Actionability

Concrete, executable guidance throughout: TypeScript schema snippets, the numbered three-deploy workflow, a real command (`npx convex run migrations:myMigration '{"dryRun": true}'`), and a copy-ready checklist. It falls short of anchor 5 only because the core migration code patterns are delegated to references rather than shown inline for the common cases.

Workflow Clarity

The multi-deploy workflow is a clearly sequenced numbered list with validation checkpoints (dry run, "Verify all documents are migrated") and a full migration checklist, satisfying the batch-operation validation requirement. Not anchor 5 because the error-recovery feedback loop is implicit — the skill says verify but never says what to do when verification fails or a deploy is rejected.

Progressive Disclosure

The body is a genuine overview: concepts, safe-vs-breaking changes, workflow, and pitfalls inline, with the two real reference files (`references/migrations-component.md`, `references/migration-patterns.md`) clearly signaled with explicit scope descriptions ("See references/migration-patterns.md for complete patterns with code examples covering: ..."). One level deep, well navigable — matches anchor 5 exactly.

Specificity

The description names the domain and several concrete actions — "Plans Convex schema and data migrations with widen-migrate-narrow and @convex-dev/migrations" — which is more than 1-2 actions but has minor coverage gaps (e.g., verification/rollback is only implied via 'zero-downtime rollouts'). It sits between anchor 3 and anchor 5, matching anchor 4's 'several specific actions; minor gaps in coverage'.

Completeness

It explicitly answers both: what ("Plans Convex schema and data migrations with widen-migrate-narrow and @convex-dev/migrations") and when ("Use for breaking schema changes, backfills, table reshaping, or zero-downtime rollouts"), with concrete trigger phrases. This matches anchor 5 exactly; it is not anchor 4 because the 'when' clause is fully explicit and specific, not merely present.

Trigger Term Quality

Trigger terms "breaking schema changes, backfills, table reshaping, or zero-downtime rollouts" are natural phrases a user with this need would say. It falls just short of anchor 5's comprehensive synonym coverage (e.g., 'migration script', 'column type change', 'backfill data' as variations), so anchor 4's 'good keyword coverage; a few natural terms missing' is the best fit.

Distinctiveness Conflict Risk

The Convex-specific niche ("Convex schema and data migrations", "widen-migrate-narrow") gives it a clear trigger surface with minimal overlap risk against generic database or ORM skills. Matches anchor 5's 'clear niche with distinct triggers'; anchor 4 would require some noticeable overlap with a closely related skill, which is not the case.