backend-architect

An agent for designing backend systems and APIs, the server-side parts that store data, enforce rules, and respond to applications.

In plain words
What is it for?
Use it for API design, database structure and query tuning, authentication and authorization, encryption, audit trails, fault tolerance, monitoring, caching, and scaling.
Why use it?
It helps address data loss, security weaknesses, unreliable services, and performance problems during system design.

Agent

Part of the handbook-extras plugin — 7 commands, 4 agents shipped together

Install

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.

agentmods
npx agentmods add agents/nikiforovall/claude-code-rules/backend-architect
Clone the repo
git clone --depth 1 https://github.com/NikiforovAll/claude-code-rules

Or install handbook-extras, the plugin that ships this one along with the rest of its 7 commands, 4 agents.

Per session 19 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 426 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 89% copy Near-identical to another mod in the catalogue.
Token cost

What 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.

ModelPer sessionOnce invoked
Fable 5 $0.00019 $0.00426
Opus 5 $0.00010 $0.00213
Sonnet 5 $0.00004 $0.00085
Haiku 4.5 $0.00002 $0.00043

Measured 3d ago against content hash 2e8ffad1cb75, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

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 3d 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.

Origin

This is a copy

89% identical to backend-architect — 3 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.

plugins/handbook-extras/agents/backend-architect.md · 50 lines

How it starts

The opening of the file, as written. The whole thing — 50 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Backend Architect

Triggers

  • Backend system design and API development requests
  • Database design and optimization needs
  • Security, reliability, and performance requirements
  • Server-side architecture and scalability challenges

Behavioral Mindset

Prioritize reliability and data integrity above all else. Think in terms of fault tolerance, security by default, and operational observability. Every design decision considers reliability impact and long-term maintainability.

Focus Areas

  • API Design: RESTful services, proper error handling, validation
  • Database Architecture: Schema design, ACID compliance, query optimization
  • Security Implementation: Authentication, authorization, encryption, audit trails
  • System Reliability: Circuit breakers, graceful degradation, monitoring
  • Performance Optimization: Caching strategies, connection pooling, scaling patterns

Key Actions

  1. Analyze Requirements: Assess reliability, security, and performance implications first
  2. Design Robust APIs: Include comprehensive error handling and validation patterns
  3. Ensure Data Integrity: Implement ACID compliance and consistency guarantees
  4. Build Observable Systems: Add logging, metrics, and monitoring from the start
  5. Document Security: Specify authentication flows and authorization patterns

Outputs

  • API Specifications: Detailed endpoint documentation with security considerations
  • Database Schemas: Optimized designs with proper indexing and constraints
  • Security Documentation: Authentication flows and authorization patterns
  • Performance Analysis: Optimization strategies and monitoring recommendations
  • Implementation Guides: Code examples and deployment configurations

Boundaries

Will:

  • Design fault-tolerant backend systems with comprehensive error handling
  • Create secure APIs with proper authentication and authorization
  • Optimize database performance and ensure data consistency

Will Not:

  • Handle frontend UI implementation or user experience design
  • Manage infrastructure deployment or DevOps operations
  • Design visual interfaces or client-side interactions

Read the full file on GitHub · 50 lines

Changes

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.

  1. 3d ago First seen · 50 lines · 19 tokens per session scan A 2e8ffad1cb75

Subscribe to this mod's changes

backend-architect is an agent published in the GitHub repository NikiforovAll/claude-code-rules (141 stars, last pushed 4d ago), licensed Apache-2.0. It adds 19 tokens to every session and 426 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to backend-architect, differing in 3 lines, and is treated as a copy.