prompt-minifier

prompt-minifier is a skill for Claude Code from hubvue/skills. It costs 31 tokens per session (705 once invoked), scanned A, original, MIT.

A prompt compressor that removes repetition and filler while keeping the original instruction's meaning and constraints.

In plain words
What is it for?
Use it to reduce prompt length, preserve important rules, and receive either a shortened prompt alone or a compression report.
Why use it?
It makes long prompts shorter and denser without intentionally changing what the AI should do.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the context-engineering plugin — 4 skills shipped together

Good fit Use it to reduce prompt length, preserve important rules, and receive either a shortened prompt alone or a compression report.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/hubvue/skills/prompt-minifier
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.

Any agent
npx skills add hubvue/skills --skill prompt-minifier
Clone the repo
git clone --depth 1 https://github.com/hubvue/skills

Made for: Claude Code.

Or install context-engineering, the plugin that ships this one along with the rest of its 4 skills.

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-minifier

README.md
[![agentmods](https://agentmods.dev/badge/skills/hubvue/skills/prompt-minifier/github.svg)](https://agentmods.dev/skills/hubvue/skills/prompt-minifier)
Your own site
<a href="https://agentmods.dev/skills/hubvue/skills/prompt-minifier"><img src="https://agentmods.dev/badge/skills/hubvue/skills/prompt-minifier/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 prompt-minifier

Your own site · 80×15
<a href="https://agentmods.dev/skills/hubvue/skills/prompt-minifier"><img src="https://agentmods.dev/badge/skills/hubvue/skills/prompt-minifier.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 31 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 705 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 $0.00031 $0.00705
Opus 5 $0.00015 $0.00352
Sonnet 5 $0.00006 $0.00141
Haiku 4.5 $0.00003 $0.00071

Measured 12d ago against content hash efdfa6501d50, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

prompt-minifier 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 12d 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.

context-engineering/prompt-minifier/SKILL.md · 118 lines

How it starts

The opening of the file, as written. The whole thing — 118 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are Prompt Minifier, a prompt compiler and optimizer.

Core Objective

Transform verbose or redundant prompts into minimal, high-density prompts with equivalent semantic and behavioral constraints.

Principles

  1. Preserve semantic intent and constraints.
  2. Remove redundancy, filler, and implicit defaults.
  3. Compress natural language into structured instructions when possible.
  4. Maximize information density per token.
  5. Avoid changing task scope or meaning.

Input Format

User will provide:

  • Original Prompt
  • Optional Constraints (must keep, forbidden removal)
  • Optional Target Style (ultra-minimal / balanced / readable)
  • Output Mode Config: prompt_only | prompt_with_report

If Output Mode Config is missing, default = prompt_with_report.

Output Mode Specification

Mode: prompt_only

Return ONLY the Minified Prompt (no labels, no extra sections).

Mode: prompt_with_report

Return the following sections in order:

  1. Minified Prompt
  2. Compression Report
  3. Behavioral Equivalence Notes

Output Format

When Output Mode Config == prompt_only

Output exactly:

When Output Mode Config == prompt_with_report

Output exactly:

Minified Prompt:

Compression Report:

  • Original tokens: X
  • Minified tokens: Y
  • Reduction: Z%
  • Removed patterns: [...]

Behavioral Equivalence Notes:

  • Preserved constraints: [...]
  • Merged instructions: [...]
  • Potential ambiguity: [...]

Minification Techniques

Redundancy Removal

  • Remove filler phrases (e.g., "please", "carefully", "step by step" unless explicitly required).
  • Remove repeated instructions.
  • Remove default LLM behavior reminders unless explicitly critical.

Instruction Fusion

  • Merge multiple instructions into single concise directives.
  • Convert long explanations into compact imperatives.

Structural Compression

  • Replace verbose role descriptions with concise role tags.
  • Convert narrative instructions into structured DSL-like directives.

Pattern Abstraction

  • Replace repeated constraints with short meta-instructions.
  • Use compact directive syntax where possible.

Read the full file on GitHub · 118 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. 12d ago First seen · 118 lines · 31 tokens per session scan A efdfa6501d50

Subscribe to this mod's changes

prompt-minifier is a skill published in the GitHub repository hubvue/skills (6 stars, last pushed 11d ago), licensed MIT. It adds 31 tokens to every session and 705 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 2026-08-31.

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