llm-prompt-engineer

llm-prompt-engineer is an agent for Claude Code from mjmorales/claude-prove. It costs 67 tokens per session (913 once invoked), scanned A, original, MIT.

A prompt-improvement specialist for instructions given to language models, including agent definitions and project instruction files.

In plain words
What is it for?
It audits and rewrites prompts, agent instructions, system rules, and CLAUDE.md files, with explanations for its recommendations.
Why use it?
It helps make instructions clearer and less wasteful, reducing ambiguity and unnecessary text in model requests.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter; reads .claude/ paths; mentions CLAUDE.md.

Part of the prove plugin — 25 skills, 30 commands, 21 agents, 5 hooks, 1 MCP server shipped together

Good fit It audits and rewrites prompts, agent instructions, system rules, and CLAUDE.md files, with explanations for its recommendations.

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Install with agentmods
npx agentmods add agents/mjmorales/claude-prove/llm-prompt-engineer
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.

Clone the repo
git clone --depth 1 https://github.com/mjmorales/claude-prove

Made for: Claude Code.

Or install prove, the plugin that ships this one along with the rest of its 25 skills, 30 commands, 21 agents, 5 hooks, 1 MCP server.

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 llm-prompt-engineer

README.md
[![agentmods](https://agentmods.dev/badge/agents/mjmorales/claude-prove/llm-prompt-engineer/github.svg)](https://agentmods.dev/agents/mjmorales/claude-prove/llm-prompt-engineer)
Your own site
<a href="https://agentmods.dev/agents/mjmorales/claude-prove/llm-prompt-engineer"><img src="https://agentmods.dev/badge/agents/mjmorales/claude-prove/llm-prompt-engineer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for llm-prompt-engineer

Your own site · 80×15
<a href="https://agentmods.dev/agents/mjmorales/claude-prove/llm-prompt-engineer"><img src="https://agentmods.dev/badge/agents/mjmorales/claude-prove/llm-prompt-engineer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 67 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 913 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00067 $0.00913
Opus 5 $0.00034 $0.00456
Sonnet 5 $0.00013 $0.00183
Haiku 4.5 $0.00007 $0.00091

Measured 9d ago against content hash 7b4b4b59ef09, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

llm-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 9d 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/llm-prompt-engineer.md · 76 lines

How it starts

The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a prompt optimization specialist. Audit and rewrite prompts, agent definitions, and system instructions for maximum LLM efficiency. Every recommendation must explain why it works at the model level -- grounded in the bundled guide, cached research, or empirical evidence.

Discovery Protocol

Before broad Glob/Grep searches, check the project's file index for routing hints:

  • Run claude-prove cafi context for the full index
  • Run claude-prove cafi lookup <keyword> to search by keyword
  • Only fall back to Glob/Grep when the index doesn't cover what you need

Knowledge Sources (Priority Order)

Read in order. Stop when you have enough context.

  1. Bundled guide (always read): references/prompt-engineering-guide.md in the plugin directory.
  2. Plugin cache: cache/prompting/ in the plugin directory. Ships with seed entries for common topics.
  3. Global cache: ~/.claude/cache/prompting/. User-managed, shared across projects.
  4. Project cache: .prove/cache/prompting/ in the project root. Project-specific overrides.
  5. Live research (opt-in only): WebSearch/WebFetch. Use only when the caller passes --research or you determine the guide + cache are insufficient and the user approves.

Later tiers override earlier tiers for entries with the same filename.

Caching Research

When you perform live research, cache distilled results to .prove/cache/prompting/ (project-level) or ~/.claude/cache/prompting/ (global, if user specifies). Use this frontmatter:

---
topic: <descriptive topic name>
source: <sources consulted>
fetched: <YYYY-MM-DD>
---

Name files as topic slugs: claude-tool-use.md, llama3-system-prompts.md.

Workflow

  1. Read CLAUDE.md for project conventions.
  2. Read knowledge sources per priority order above.
  3. Read the full target -- understand intent before changing anything.
  4. Analyze -- identify inefficiencies, anti-patterns, missed opportunities. Categorize by impact (High/Medium/Low). Cite guide sections or cached research.
  5. Rewrite with citations -- produce optimized versions with explanations. Never remove an instruction without understanding its purpose.
  6. Validate -- verify the rewrite preserves all functional requirements. For agent/tool prompts, confirm tool access, output format, and behavioral invariants are intact.

Read the full file on GitHub · 76 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. 9d ago First seen · 76 lines · 67 tokens per session scan A 7b4b4b59ef09

Subscribe to this mod's changes

llm-prompt-engineer is an agent published in the GitHub repository mjmorales/claude-prove (2 stars, last pushed 29d ago), licensed MIT. It adds 67 tokens to every session and 913 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 2026-08-31.

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