Conciseness

The body is lean and project-specific throughout — "The Caddyfile block label becomes authcrunch's required credential `name`", "Do not add `name` or `kind` inside the block; caddy-security injects `name` from `<label>`, and unsupported inner keys fail parsing" — with no explanation of concepts Claude already knows. Every section (Purpose, Credentials vs Secrets, Shape, Guidance, Fixtures) earns its tokens.

Actionability

Guidance is fully executable: a complete copy-paste Caddyfile block ("credentials smtp_root { username root ... domain example.com }"), the exact accepted directives ("username <username>", "password <password>", "domain <name>"), and both common password patterns ("{env.SMTP_PASSWORD}" and "secrets:smtp:password") plus quoting rules ("Quote values containing spaces").

Workflow Clarity

For a single-purpose configuration skill the task is unambiguous: shape, required vs optional fields ("`username` and `password` are required... `domain` is optional"), and matching rules ("a messaging provider's `credentials <credential_name>` value must match the resolved credentials block label") are all explicit. It falls short of 5 because validation is described via named fixtures rather than an explicit run-the-tests checkpoint in the workflow itself.

Progressive Disclosure

No bundle files exist, and none are needed: the ~110-line body is well organized into clear sections, with one-level-deep, clearly signaled sibling references ("[configuration-secrets](../configuration-secrets/SKILL.md) owns manager blocks and lookup rules", "[runtime resolution](../configuration-runtime-resolution/SKILL.md#what-gets-resolved)", "[configuration-messaging](../configuration-messaging/SKILL.md)") each deferring detail the body doesn't duplicate. Navigation is easy and no content that belongs in a separate file is inlined.

Specificity

"Configure reusable named username/password credentials for messaging consumers, including optional domains and runtime values" names the domain (credential configuration for messaging consumers) and enumerates concrete specifics (named credentials, username/password, optional domains, runtime values), leaving only minor coverage gaps. It is not a 5 because a single action verb ("Configure") is given rather than multiple distinct concrete actions.

Completeness

The "what" is clear and concrete (configure reusable named credentials with optional domains and runtime values), but there is no "Use when..." clause or equivalent explicit trigger guidance; the LDAP sentence is a boundary redirect, not a usage trigger. Per the judging guideline, a missing 'Use when...' clause caps completeness at 3.

Trigger Term Quality

Natural terms present include "username/password", "credentials", "messaging consumers", "domains", and "LDAP bind credentials" — good keyword coverage for the niche. A few natural terms users would say are missing, such as "SMTP", "email", or "Caddyfile", keeping it below a 5.

Distinctiveness Conflict Risk

"Configure reusable named username/password credentials for messaging consumers" carves a clear niche, and "LDAP bind credentials belong to identity stores" explicitly steers a neighboring use case away. It is not a 5 because the description does not mention the adjacent secrets-lookup capability, leaving minor overlap risk with sibling configuration skills.