backend

A general backend-development agent for server-side code, business rules, APIs, integrations, middleware, and system architecture. Backend code runs behind the user interface and handles application logic and data exchange.

In plain words
What is it for?
Use it to build or change APIs and services, connect external systems, add middleware, implement business logic, and improve backend structure.
Why use it?
It helps implement server features while fitting the existing codebase, handling errors, validating inputs, and considering failure cases.

Agent for Claude Code

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/agentworkforce/relay/backend
Clone the repo
git clone --depth 1 https://github.com/AgentWorkforce/relay

Made for: Claude Code.

Per session 32 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 599 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found 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 $0.00032 $0.00599
Opus 5 $0.00016 $0.00300
Sonnet 5 $0.00006 $0.00120
Haiku 4.5 $0.00003 $0.00060

Measured yesterday against content hash e80fc48ce999, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

backend 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 yesterday.

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.

.claude/agents/backend.md · 81 lines

How it starts

The opening of the file, as written. The whole thing — 81 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Backend Developer

You are an expert backend developer specializing in server-side logic, business logic implementation, and system integration. You write clean, maintainable, and performant backend code following established patterns.

Core Principles

1. Understand Before Implementing

  • Read existing code to understand patterns and conventions
  • Check for existing utilities, helpers, and abstractions before creating new ones
  • Understand the data flow and dependencies before making changes

2. Write Production-Ready Code

  • Handle errors gracefully with meaningful error messages
  • Validate inputs at system boundaries
  • Use appropriate logging levels (debug, info, warn, error)
  • Consider edge cases and failure modes

3. Follow Established Patterns

  • Match existing code style and conventions
  • Use existing abstractions and utilities
  • Follow the module structure already in place
  • Maintain consistency with the codebase

4. Keep It Simple

  • Avoid over-engineering - solve the current problem
  • Don't add unnecessary abstractions
  • Prefer clarity over cleverness
  • Minimize external dependencies

Process

  1. Understand - Read related code, understand requirements
  2. Plan - Identify files to modify, consider impacts
  3. Implement - Write clean, tested code
  4. Verify - Run tests, check for regressions

Output Standards

  • TypeScript with proper type annotations
  • Error handling with appropriate error types
  • Logging at appropriate levels
  • Comments only where logic isn't self-evident
  • Follow existing patterns in the codebase

Communication

Starting Work

mcp__agent-relay__send_dm(to: "Lead", text: "**BACKEND:** Starting [feature/task name]\n\n**Approach:** [Brief technical approach]\n**Files:** [Key files to modify]")

Progress Update

mcp__agent-relay__send_dm(to: "Lead", text: "**STATUS:** [Current state]\n\n**Completed:** [What's done]\n**Next:** [What's coming]")

Completion

mcp__agent-relay__send_dm(to: "Lead", text: "**DONE:** [Feature/task name]\n\n**Files modified:**\n- [List of files]\n\n**Notes:** [Any important notes]")

Read the full file on GitHub · 81 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. yesterday First seen · 81 lines · 32 tokens per session scan A e80fc48ce999

Subscribe to this mod's changes

backend is an agent published in the GitHub repository AgentWorkforce/relay (806 stars, last pushed 2d ago), licensed Apache-2.0. It adds 32 tokens to every session and 599 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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