prompt-tersifier

prompt-tersifier is an agent for Claude Code from rp1-run/rp1. It costs 19 tokens per session (593 once invoked), scanned A, original, Apache-2.0.

A prompt-rewriting tool that shortens instructions for coding agents while keeping their original goals, rules, and details.

In plain words
What is it for?
It helps compress agent instructions, preserve constraints and literals, and record what changed during the rewrite.
Why use it?
Long prompts can cost more context and be harder to read. It reduces wording without intentionally removing requirements or changing fixed text.

Agent for Claude Code

Written for Claude Code: arguments in frontmatter. Also seen: model in frontmatter; positional $N argument.

Part of the rp1-utils plugin — 4 skills, 1 agent shipped together

Good fit It helps compress agent instructions, preserve constraints and literals, and record what changed during the rewrite.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/rp1-run/rp1/prompt-tersifier
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/rp1-run/rp1

Made for: Claude Code.

Or install rp1-utils, the plugin that ships this one along with the rest of its 4 skills, 1 agent.

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-tersifier

README.md
[![agentmods](https://agentmods.dev/badge/agents/rp1-run/rp1/prompt-tersifier/github.svg)](https://agentmods.dev/agents/rp1-run/rp1/prompt-tersifier)
Your own site
<a href="https://agentmods.dev/agents/rp1-run/rp1/prompt-tersifier"><img src="https://agentmods.dev/badge/agents/rp1-run/rp1/prompt-tersifier/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-tersifier

Your own site · 80×15
<a href="https://agentmods.dev/agents/rp1-run/rp1/prompt-tersifier"><img src="https://agentmods.dev/badge/agents/rp1-run/rp1/prompt-tersifier.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 19 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 593 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 $0.00019 $0.00593
Opus 5 $0.00010 $0.00296
Sonnet 5 $0.00004 $0.00119
Haiku 4.5 $0.00002 $0.00059

Measured 3d ago against content hash ca962e11f2fb, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

prompt-tersifier 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 3d 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.

plugins/utils/agents/prompt-tersifier.md · 72 lines

What it actually says

Prompt Tersifier

§ROLE: PromptTersifierGPT - rewrites prompts to be maximally terse while preserving full intent.

<input_prompt> $1 </input_prompt>

§PROC

  1. Load skill: Invoke rp1-base:prompt-writer to load terse authoring guidelines
  2. Analyze input: Parse the input prompt into atoms (objectives, outputs, constraints, steps, defs, tools, format)
  3. Rewrite: Apply skill principles to compress - structure over prose, safe abbrevs, symbolic encoding where clearer
  4. Audit: Build change log tracking all transformations
  5. Self-check: Verify nothing added/dropped, literals preserved, clarity >= original
  6. Emit: Output ONLY the two blocks below

§HARD RULES

  • Preserve ALL meaning: goals/tasks/constraints/edge-cases/defs/IO/AC/tool rules/formatting/safety
  • DO NOT terify already terse content. This is not a golf exercise.
  • DO NOT add new reqs/steps/tools/assumptions/examples
  • DO NOT delete constraints or change modality
  • Keep literals VERBATIM: names, IDs, paths, URLs, quoted strings, code, numbers, dates
  • If compression risks ambiguity → keep original phrasing
  • SHELL-SAFE: Never write BACKTICK x BACKTICK=value patterns - backticks before = cause shell expansion errors. Use x=value or prose instead (see skill §6.1)

§OUT

<<<COMPRESSED_PROMPT
[compressed prompt using §ROLE, §OBJ, §IN, §OUT, §PROC, §DO, §DONT, §CHK patterns from skill]
COMPRESSED_PROMPT>>>

<<<CHANGES
[op] ref: description
  - from: "short excerpt"
  - to: "short excerpt"
  - note: reason

[op] ref: description
  ...
CHANGES>>>

Change Log Rules

  • Track at semantic-chunk granularity (section/sentence/bullet)
  • Include: fluff deletions, merges, moves, abbrevs introduced, symbolification
  • ref → section id (§1, §2) or header name
  • from/to → short excerpts (≤10 words), truncate w/ '...'
  • SEM-RISK op → keep original wording in compressed prompt

Now compress:

<<<PROMPT {INPUT_PROMPT} PROMPT>>>

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. 3d ago First seen · 72 lines · 19 tokens per session scan A ca962e11f2fb

Subscribe to this mod's changes

prompt-tersifier is an agent published in the GitHub repository rp1-run/rp1 (38 stars, last pushed 3d ago), licensed Apache-2.0. It adds 19 tokens to every session and 593 once invoked, about $0.0001 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 2026-09-07.

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