api-and-interface-design

Guides stable API and interface design. Use when designing APIs, module boundaries, or any public interface. Use when creating REST or GraphQL endpoints, defining type contracts between modules, or establishing boundaries between frontend and backend.

Quality

—

Does it follow best practices?

Impact

—

No eval scenarios have been run

Securityby

Passed

No known issues

Quality

Content

77%

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

A highly actionable, well-structured design skill with concrete code examples and a verification checklist. Its weaknesses are mild verbosity around well-known concepts and a monolithic structure that doesn't progressively disclose deeper material.

Suggestions

Tighten or drop explanations Claude already knows: replace the quoted Hyrum's Law definition and HTTP status-code comments with just the actionable design implications, keeping the named principles as signposts.

Split the detailed "REST API Patterns" and "TypeScript Interface Patterns" sections into separate reference files (e.g. rest-patterns.md, typescript-patterns.md) linked from a concise overview, so the main SKILL.md stays a lean entry point.

Move the "Common Rationalizations" table into a reference file or condense it to the highest-value rows to reduce inline length while keeping the counterarguments discoverable.

Dimension	Reasoning	Score
Conciseness	Mostly efficient and actionable, but spends tokens explaining concepts Claude already knows — the Hyrum's Law definition and elaboration, the diamond-dependency explanation, and the HTTP status-code mapping (400→client data, 500→server) — that could be tightened.	2 / 3
Actionability	Provides fully executable TypeScript interfaces, an Express route handler with Zod-style validation, discriminated-union and branded-type patterns, plus concrete REST endpoint and pagination shapes that are copy-paste ready.	3 / 3
Workflow Clarity	The numbered Core Principles (1 Contract First → 5 Predictable Naming) give a loose design sequence, and the final "Verification" section provides an explicit checklist of validation checkpoints to confirm a finished design.	3 / 3
Progressive Disclosure	Sections are well-organized with clear headers, but the skill is a monolithic ~280-line single file with no content split into reference files and no bundle references, so there is no one-level-deep progressive disclosure.	2 / 3
	Total	10 / 12 Passed

Description

100%

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A strong description that clearly states both the capability and concrete invocation triggers using natural, third-person language. It is specific, complete, and distinguishable from sibling skills.

Dimension	Reasoning	Score
Specificity	Enumerates multiple specific concrete design activities — "designing APIs, module boundaries, or any public interface", "creating REST or GraphQL endpoints", "defining type contracts between modules", "establishing boundaries between frontend and backend" — rather than vague language.	3 / 3
Completeness	Explicitly states what it does ("Guides stable API and interface design") and gives two explicit "Use when…" trigger clauses answering when to invoke it.	3 / 3
Trigger Term Quality	Covers natural terms a user would say ("designing APIs", "module boundaries", "REST or GraphQL endpoints", "type contracts", "frontend and backend") with good variation rather than jargon.	3 / 3
Distinctiveness Conflict Risk	A clear niche (API/interface design) with distinct triggers; unlikely to fire for unrelated skills.	3 / 3
	Total	12 / 12 Passed

Validation

100%

Warnings & errors only

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 16 / 16 Passed

Validation for skill structure

No warnings or errors.

Repository: addyosmani/agent-skills
Commit: 70b7506

Reviewed: 3 days ago

Table of Contents

Discovery Implementation Validation

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