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, confirm these inputs. If any is unknown or vague, ASK — do not assume:

• 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)

Stop rule: ask only the 2-3 that most change the output. If the user says "just draft it," proceed and list your assumptions at the top of the artifact.

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