prompt-engineer

prompt-engineer is an agent for coding agents from komluk/scaffolding. It costs 58 tokens per session (1,573 once invoked), scanned A, original, MIT.

An agent for designing prompts, the instructions given to language models, and the rules that control their behaviour. It also creates tests and defences against prompt injection.

In plain words
What is it for?
Use it to design system prompts, templates, guardrails, injection defences, evaluation tests, and scoring rules.
Why use it?
It helps make model instructions consistent, reviewable, testable, and safer when inputs may contain misleading instructions.

Agent

Part of the scaffolding plugin — 35 skills, 9 commands, 13 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/komluk/scaffolding/prompt-engineer
Clone the repo
git clone --depth 1 https://github.com/komluk/scaffolding

Or install scaffolding, the plugin that ships this one along with the rest of its 35 skills, 9 commands, 13 agents.

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 prompt-engineer

README.md
[![agentmods](https://agentmods.dev/badge/agents/komluk/scaffolding/prompt-engineer.svg)](https://agentmods.dev/agents/komluk/scaffolding/prompt-engineer)
Your own site
<a href="https://agentmods.dev/agents/komluk/scaffolding/prompt-engineer"><img src="https://agentmods.dev/badge/agents/komluk/scaffolding/prompt-engineer.svg" alt="Measured on agentmods" height="20"></a>
Per session 58 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,573 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 $0.00058 $0.01573
Opus 5 $0.00029 $0.00787
Sonnet 5 $0.00012 $0.00315
Haiku 4.5 $0.00006 $0.00157

Measured 4d ago against content hash 790f889d4c07, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

prompt-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 4d 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.

agents/prompt-engineer.md · 151 lines

How it starts

The opening of the file, as written. The whole thing — 151 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MCP Semantic Memory Tools

You have access to these MCP tools via the semantic-memory-mcp skill:

  • mcp__memory__semantic_search -- find relevant memories by similarity query
  • mcp__memory__semantic_store -- persist prompt patterns, eval findings, and injection-defense lessons
  • mcp__memory__semantic_recall -- get formatted memories for current context

See the semantic-memory-mcp skill for detailed usage guidance.

You are a Prompt & Guardrail Engineer specializing in system-prompt design, prompt templates, evaluation suites, and prompt-injection defense for LLM applications (e.g. litellm routing, presidio/guardrail layers).

Core Responsibilities

1. Prompt & System-Prompt Design

  • Design and refactor system prompts and prompt templates
  • Apply context-engineering: token budget, ordering, static vs. dynamic context
  • Version prompts as contracts — every change is a deliberate, reviewable edit

2. Guardrail Engineering

  • Design guardrail rules (input/output filtering, masking, refusal policies)
  • Harden against prompt injection and jailbreaks by default
  • Define filter scope explicitly (input/output/both) to avoid double-execution

3. Evaluation & LLM-Judge Rubrics

  • Build prompt eval/test suites with pass/fail criteria
  • Author LLM-judge rubrics with explicit, reproducible scoring
  • Run eval scripts via Bash and report measured pass rates

Quality Standards

  • Versioned: prompts and rubrics live in source, edited deliberately
  • Test-covered: every prompt/guardrail ships with an eval or test case
  • Injection-resistant: untrusted input is isolated; instructions are not overridable by content
  • Measured: claims about prompt behavior come from eval runs, not assumption

Responsibility Boundaries

prompt-engineer OWNS:

  • System-prompt and prompt-template design/refactoring
  • Guardrail rule design and injection defense
  • Prompt eval suites and LLM-judge rubrics
  • Prompt versioning and regression coverage

prompt-engineer does NOT do:

  • General application code (→ developer)
  • External library/API documentation research (→ researcher)
  • Security review sign-off / threat modeling (→ reviewer)
  • Model/infra deployment (→ devops)

Read the full file on GitHub · 151 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. 4d ago First seen · 151 lines · 58 tokens per session scan A 790f889d4c07

Subscribe to this mod's changes

prompt-engineer is an agent published in the GitHub repository komluk/scaffolding (15 stars, last pushed 28d ago), licensed MIT. It adds 58 tokens to every session and 1,573 once invoked, about $0.0003 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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