API Design Reviewer

Comprehensive analysis and review of REST API designs against conventions, best practices, and industry standards. Helps engineering teams build consistent, maintainable, well-designed APIs through automated linting, breaking-change detection, and design scorecards.

Core Capabilities

• API linting & convention analysis — resource naming (kebab-case URLs, camelCase fields), HTTP method usage, URL structure, status-code compliance, error-format consistency, and documentation coverage.
• Breaking change detection — endpoint removal, response-shape changes, field removal/rename, type changes, new required fields, and status-code changes between two spec versions, with migration guides.
• API design scoring — weighted scorecard across Consistency (30%), Documentation (20%), Security (20%), Usability (15%), and Performance (15%), with letter grades A–F and recommendations.

When to Use

• Designing a new REST API or reviewing an API contract.
• Validating an OpenAPI/Swagger spec against REST conventions.
• Managing API versioning and detecting breaking changes between releases.
• Gating deployments on API design quality in CI.

Clarify First

Before producing the review, settle the inputs below. When one is missing or vague and would change the result, ask about it; when it wouldn't, use a sensible default and say which one you used.

• Which output: lint report, design scorecard, or breaking-change detection (selects api_linter.py, api_scorecard.py, or breaking_change_detector.py).
• Spec file(s): the OpenAPI/Swagger JSON, or the two versions to diff (the input the tools parse).
• Quality bar / CI gate: minimum grade or fail-on-breaking (sets --min-grade / --exit-on-breaking and how strict the verdict is).

Ask about the two or three inputs that matter most for this request, not the whole list. If the user wants a result straight away, produce it and state your assumptions at the top.

Tools

Tool	Purpose	Command
api_linter.py	Lint an OpenAPI/Swagger JSON spec for REST conventions and best practices	python scripts/api_linter.py openapi.json --format json
breaking_change_detector.py	Detect breaking changes between two spec versions (with migration guides)	python scripts/breaking_change_detector.py v1.json v2.json --exit-on-breaking
api_scorecard.py	Score API design quality across 5 weighted dimensions (A–F grades)	python scripts/api_scorecard.py openapi.json --min-grade B

References

Load the reference that matches the task — keep this file lean and pull detail on demand:

• references/rest-design-patterns.md — REST naming/method/URL principles, versioning strategies, pagination patterns, error formats and status codes, auth/RBAC patterns, rate limiting, HATEOAS, idempotency, backward-compatibility rules, OpenAPI validation, performance, and security best practices. Read when designing or reviewing endpoints.
• references/tooling-ci-and-troubleshooting.md — the three tools' features, CI/CD and pre-commit integration, best-practices and anti-pattern checklists, troubleshooting table, success criteria, and full CLI flag references. Read when wiring tools into pipelines or debugging.
• references/rest_design_rules.md — detailed REST design rules reference (resources vs actions, HTTP method semantics with worked examples). Read for an in-depth rules catalog.
• references/api_antipatterns.md — common API anti-patterns (verb-based URLs / RPC trap and more) with bad/good examples and recommended fixes. Read when auditing an existing API for design smells.

Scope & Limitations

This skill covers:

• Linting OpenAPI 3.x and Swagger 2.0 JSON specifications against REST conventions
• Detecting breaking, potentially-breaking, and non-breaking changes between two spec versions
• Scoring API design quality across consistency, documentation, security, usability, and performance
• Generating actionable migration guides when breaking changes are found

This skill does NOT cover:

• Runtime API testing, load testing, or contract testing (see api-test-suite-builder)
• GraphQL, gRPC, or WebSocket API design review
• Auto-generation of OpenAPI specs from code or server stubs
• Authentication flow implementation or OAuth server configuration (see senior-security in engineering/)

Integration Points

Skill	Integration	Data Flow
engineering/api-test-suite-builder	Generate test cases from linter findings	Linter issues feed into test plan priorities for endpoint validation
engineering/changelog-generator	Document breaking changes in release notes	Breaking change detector output provides structured change data for changelogs
engineering/ci-cd-pipeline-builder	Gate deployments on API quality	Scorecard grade and linter exit codes integrate as pipeline quality gates
engineering/senior-backend	Review API implementation against design	Scorecard recommendations guide backend refactoring decisions
engineering/code-reviewer	Enrich PR reviews with API analysis	Linter and breaking change reports attach to PR review comments
engineering/release-manager	Validate version bumps match change severity	Breaking change detector severity levels inform semver version decisions