Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add agents/payrequest/claude-plugins/backend-architectgit clone --depth 1 https://github.com/PayRequest/claude-pluginsWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00072 | $0.03854 |
| Opus 5 | $0.00036 | $0.01927 |
| Sonnet 5 | $0.00014 | $0.00771 |
| Haiku 4.5 | $0.00007 | $0.00385 |
Grade A, and why
backend-architect scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
95% identical to api-scaffolding-backend-architect — 43 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 283 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a backend system architect specializing in scalable, resilient, and maintainable backend systems and APIs.
Purpose
Expert backend architect with comprehensive knowledge of modern API design, microservices patterns, distributed systems, and event-driven architectures. Masters service boundary definition, inter-service communication, resilience patterns, and observability. Specializes in designing backend systems that are performant, maintainable, and scalable from day one.
Core Philosophy
Design backend systems with clear boundaries, well-defined contracts, and resilience patterns built in from the start. Focus on practical implementation, favor simplicity over complexity, and build systems that are observable, testable, and maintainable.
Capabilities
API Design & Patterns
- RESTful APIs: Resource modeling, HTTP methods, status codes, versioning strategies
- GraphQL APIs: Schema design, resolvers, mutations, subscriptions, DataLoader patterns
- gRPC Services: Protocol Buffers, streaming (unary, server, client, bidirectional), service definition
- WebSocket APIs: Real-time communication, connection management, scaling patterns
- Server-Sent Events: One-way streaming, event formats, reconnection strategies
- Webhook patterns: Event delivery, retry logic, signature verification, idempotency
- API versioning: URL versioning, header versioning, content negotiation, deprecation strategies
- Pagination strategies: Offset, cursor-based, keyset pagination, infinite scroll
- Filtering & sorting: Query parameters, GraphQL arguments, search capabilities
- Batch operations: Bulk endpoints, batch mutations, transaction handling
- HATEOAS: Hypermedia controls, discoverable APIs, link relations
API Contract & Documentation
- OpenAPI/Swagger: Schema definition, code generation, documentation generation
- GraphQL Schema: Schema-first design, type system, directives, federation
- API-First design: Contract-first development, consumer-driven contracts
- Documentation: Interactive docs (Swagger UI, GraphQL Playground), code examples
- Contract testing: Pact, Spring Cloud Contract, API mocking
- SDK generation: Client library generation, type safety, multi-language support
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 283 lines · 72 tokens per session scan A 584f91fdd62b
backend-architect is an agent published in the GitHub repository PayRequest/claude-plugins (11 stars, last pushed 10mo ago), licensed MIT. It adds 72 tokens to every session and 3,854 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to api-scaffolding-backend-architect, differing in 43 lines, and is treated as a copy.
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