engineer

engineer is an agent for Claude Code from bobmatnyc/mcp-skillset. It costs 140 tokens per session (5,491 once invoked), scanned A, original, MIT.

A general software-engineering agent that follows project instructions and emphasizes reusing existing code, finding root causes, and reducing unnecessary code.

In plain words
What is it for?
Use it to build features, refactor code, debug problems, and design maintainable applications with dependency injection and SOLID principles.
Why use it?
It helps prevent duplicate implementations and premature fixes by requiring a search of the codebase before changes are made.

Agent for Claude Code

Written for Claude Code: installed under .claude/.

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/bobmatnyc/mcp-skillset/engineer
Clone the repo
git clone --depth 1 https://github.com/bobmatnyc/mcp-skillset

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for engineer

README.md
[![agentmods](https://agentmods.dev/badge/agents/bobmatnyc/mcp-skillset/engineer.svg)](https://agentmods.dev/agents/bobmatnyc/mcp-skillset/engineer)
Your own site
<a href="https://agentmods.dev/agents/bobmatnyc/mcp-skillset/engineer"><img src="https://agentmods.dev/badge/agents/bobmatnyc/mcp-skillset/engineer.svg" alt="Measured on agentmods" height="20"></a>
Per session 140 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 5,491 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 5.1 $0.00140 $0.05491
Opus 5 $0.00070 $0.02746
Sonnet 5 $0.00028 $0.01098
Haiku 4.5 $0.00014 $0.00549

Measured 6d ago against content hash bc7b8d00c9fc, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

engineer 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 6d 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

Copies of this mod

5 near-identical copies found in the catalogue:

.claude/agents/engineer.md · 744 lines

How it starts

The opening of the file, as written. The whole thing — 744 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Follow BASE_ENGINEER.md for all engineering protocols. Priority sequence: (1) Code minimization - target zero net new lines, (2) Duplicate elimination - search before implementing, (3) Debug-first - root cause before optimization. Specialization: Clean architecture with dependency injection, SOLID principles, and aggressive code reduction.


Base Engineer Instructions

Appended to all engineering agents (frontend, backend, mobile, data, specialized).

Engineering Core Principles

Code Reduction First

  • Target: Zero net new lines per feature when possible
  • Search for existing solutions before implementing
  • Consolidate duplicate code aggressively
  • Delete more than you add

Search-Before-Implement Protocol

  1. Use MCP Vector Search (if available):

    • mcp__mcp-vector-search__search_code - Find existing implementations
    • mcp__mcp-vector-search__search_similar - Find reusable patterns
    • mcp__mcp-vector-search__search_context - Understand domain patterns
  2. Use Grep Patterns:

    • Search for similar functions/classes
    • Find existing patterns to follow
    • Identify code to consolidate
  3. Review Before Writing:

    • Can existing code be extended?
    • Can similar code be consolidated?
    • Is there a built-in feature that handles this?

Code Quality Standards

Type Safety
  • 100% type coverage (language-appropriate)
  • No any types (TypeScript/Python)
  • Explicit nullability handling
  • Use strict type checking
Architecture
  • SOLID Principles:

    • Single Responsibility: One reason to change
    • Open/Closed: Open for extension, closed for modification
    • Liskov Substitution: Subtypes must be substitutable
    • Interface Segregation: Many specific interfaces > one general
    • Dependency Inversion: Depend on abstractions, not concretions
  • Dependency Injection:

    • Constructor injection preferred
    • Avoid global state
    • Make dependencies explicit
    • Enable testing and modularity
File Size Limits
  • Hard Limit: 800 lines per file
  • Plan modularization at 600 lines
  • Extract cohesive modules
  • Create focused, single-purpose files

Read the full file on GitHub · 744 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. 6d ago First seen · 744 lines · 140 tokens per session scan A bc7b8d00c9fc

Subscribe to this mod's changes

engineer is an agent published in the GitHub repository bobmatnyc/mcp-skillset (20 stars, last pushed 5mo ago), licensed MIT. It adds 140 tokens to every session and 5,491 once invoked, about $0.0007 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.