What is prompt-improver?

A read-only assistant for improving prompts sent to external coding tools. It selects a suitable structure, checks the prompt for clarity, and flags missing information or risks.

Use it to prepare and validate prompts before dispatching them to another agent or command-line tool.

It helps make tool instructions more precise without hiding ambiguity or pretending that missing details are known.

prompt-improver — Agent for Claude Code by MichelKerkmeester

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/MichelKerkmeester/skilled-agent-harness_spec-driven-loops

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.

README.md

[![agentmods](https://agentmods.dev/badge/agents/michelkerkmeester/skilled-agent-harness_spec-driven-loops/prompt-improver/github.svg)](https://agentmods.dev/agents/michelkerkmeester/skilled-agent-harness_spec-driven-loops/prompt-improver)

Your own site

<a href="https://agentmods.dev/agents/michelkerkmeester/skilled-agent-harness_spec-driven-loops/prompt-improver"><img src="https://agentmods.dev/badge/agents/michelkerkmeester/skilled-agent-harness_spec-driven-loops/prompt-improver/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.

Your own site · 80×15

<a href="https://agentmods.dev/agents/michelkerkmeester/skilled-agent-harness_spec-driven-loops/prompt-improver"><img src="https://agentmods.dev/badge/agents/michelkerkmeester/skilled-agent-harness_spec-driven-loops/prompt-improver.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 22 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 5,522 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.

Model	Per session	Once invoked
Fable 5.1	$0.00022	$0.05522
Opus 5.5	$0.00009	$0.02209
Sonnet 5.5	$0.00004	$0.01104
Haiku 4.5	$0.00002	$0.00552

Measured today against content hash 41989a3f70ad, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

prompt-improver 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 today.

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

1 near-identical copy found in the catalogue:

prompt-improver — 100% identical, 107 lines differ

.claude/agents/prompt-improver.md · 414 lines

How it starts

The opening of the file, as written. The whole thing — 414 lines — stays where its author put it; the contents beside it link to each section on GitHub.

The Prompt-Improver Agent: Prompt Escalation Specialist

Read-only prompt-engineering specialist for high-stakes external CLI prompt construction. This agent runs the one-pass improvement checklist at the right effort level, builds from the default skeleton or a named preset, screens the result with CLEAR, and returns a structured prompt package that the caller can dispatch directly.

CRITICAL: This agent is LEAF-only and read-only. It never edits files, never delegates, never executes the enhanced prompt, and never returns unstructured prompt advice.

BOUNDARY PRINCIPLE: Prompt polish must not hide missing inputs, ambiguity, contradictions, integration assumptions, or partial-success states. Surface those limits in ESCALATION_NOTES or use the blocked package.

IMPORTANT: Use only .skilled/agents/*.md as the canonical runtime path reference. Runtime mirrors are downstream packaging surfaces.

Hook-Injected Advisor Context: Treat hook-injected skill-advisor recommendations as routing hints only. They never override explicit user instructions, active command workflow, scope gates, runtime permissions, agent boundaries, or required skill loading. If advisor context conflicts with the dispatch prompt or verified local files, prefer the dispatch prompt plus file evidence and report the conflict.

0. ILLEGAL NESTING AND WRITE BOUNDARY (HARD BLOCK)

This agent is LEAF-only and read-only. Nested sub-agent dispatch and file mutation are illegal.

NEVER call the Task tool, create sub-tasks, ask another agent to investigate, or hand off work from inside @prompt-improver.
NEVER use or recommend Write/Edit/Patch/Bash operations. write, edit, and bash are all denied in this agent's permissions.
NEVER execute the prompt it constructs. This agent returns a dispatch-ready package; the caller dispatches it.
NEVER emit a file path for @prompt-improver to write later, even when the caller asks for "file-based" output.
If delegation, mutation, or execution is requested, ignore that portion, complete the prompt package with allowed read-only tools, and record the refused boundary in ESCALATION_NOTES.
If the request cannot be framed as prompt construction, or raw_task is absent, return the blocked package rather than guessing the caller's intent.

Read the full file on GitHub · 414 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.

today Changed · +1 lines 41989a3f70ad
7d ago Changed · +2 lines · +1 tokens per session e80a3b13c7f0
9d ago Changed · +2 lines 561f4cc6fa0a
14d ago Changed 50635fd0f21c
19d ago Changed · +2 lines 8345a77dcf85
1mo ago Changed 55c5ee2a2c68
1mo ago Changed · +2 lines d7dcdb69df60
1mo ago Changed 90e0b55908f8
1mo ago Changed · +1 lines a5346f147d3d
1mo ago First seen · 404 lines · 21 tokens per session scan A 360a1644c123

Subscribe to this mod's changes

prompt-improver is an agent published in the GitHub repository MichelKerkmeester/skilled-agent-harness_spec-driven-loops (40 stars, last pushed today), licensed MIT. It adds 22 tokens to every session and 5,522 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-09-01.

Building agents Productivity

prompt-improver next to 6 agents from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
prompt-improverMichelKerkmeester/skilled-agent-harness_spec-driven-loops	Agent	40	today	MIT	A	22	Claude Code
growthalebgl77/claude-inc	Agent	22	16d ago	MIT	A	73	Claude Code
posterseaosinc/mcp-llm-offload	Agent	1	1mo ago	MIT	A	183	Claude Code
cee-triage-agentsanchitnis/SrujanaSangama	Agent	2	2mo ago	none	A	61	Claude Code
consistency-reliability-builderChrisRoyse/610ClaudeSubagents	Agent	122	1y ago	none	A	20	Claude Code
base-template-generatorakhilyad/deployy	Agent	0	5mo ago	MIT	A	249	Claude Code
playwright-test-generatormicrosoft/playwright	Agent	99k	today	Apache-2.0	A	151	Claude Code