Can it handle projects that use multiple different APIs?

Yes, for multi-protocol systems, it generates a 'Contract Index' to synchronize data models and error codes across different interfaces like REST and WebSockets.

Does this skill write the actual backend code?

No, it focuses strictly on the 'contract' layer to ensure architectural alignment and a single source of truth before implementation begins.

How does it ensure the API matches product requirements?

The skill performs a mandatory PRD-to-Contract mapping during its self-check phase to ensure that 100% of the product requirements are addressed in the specification.

What protocols does the API Writer support?

It supports a wide range of protocols including HTTP/REST, GraphQL, gRPC, WebSocket, SSE, Webhooks, and even SDK/Library interfaces or file formats.

API Contract & Specification Writer

Name: API Contract & Specification Writer
Author: TestAny-io

byTestAny-io

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API Development

Generates standardized API contracts and protocol specifications to serve as a single source of truth for cross-team development.

About

The API Writer skill bridges the gap between product requirements and technical implementation by generating precise, reviewable API specifications. It supports a vast array of protocols including REST, GraphQL, gRPC, and Webhooks, ensuring that architectural boundaries and data ownership are defined before coding begins. By enforcing a 'contract-first' approach, it reduces communication drift between frontend and backend teams and maintains consistency through automated mapping of PRDs to interface definitions.

Key Features

Standardized templates for SDK interfaces, file formats, and IPC/CLI tools
6 GitHub stars
Multi-protocol support including REST, GraphQL, gRPC, WebSocket, and Webhooks
Automated PRD-to-Contract requirement mapping for 100% coverage
Contract Indexing for complex systems using multiple communication patterns
Consistency self-checks for data models, error codes, and permissions

Use Cases

Architecting complex microservices that require unified event and sync protocols
Documenting public-facing SDKs and libraries to ensure backward compatibility
Generating formal API specifications immediately following PRD approval

About

Key Features

Standardized templates for SDK interfaces, file formats, and IPC/CLI tools
6 GitHub stars
Multi-protocol support including REST, GraphQL, gRPC, WebSocket, and Webhooks
Automated PRD-to-Contract requirement mapping for 100% coverage
Contract Indexing for complex systems using multiple communication patterns
Consistency self-checks for data models, error codes, and permissions

Use Cases

Architecting complex microservices that require unified event and sync protocols
Documenting public-facing SDKs and libraries to ensure backward compatibility
Generating formal API specifications immediately following PRD approval