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.
npx skills add SynapSync/skills-registry --skill prompt-improvergit clone --depth 1 https://github.com/SynapSync/skills-registryWrote 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.
[](https://agentmods.dev/skills/synapsync/skills-registry/prompt-improver)<a href="https://agentmods.dev/skills/synapsync/skills-registry/prompt-improver"><img src="https://agentmods.dev/badge/skills/synapsync/skills-registry/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.
<a href="https://agentmods.dev/skills/synapsync/skills-registry/prompt-improver"><img src="https://agentmods.dev/badge/skills/synapsync/skills-registry/prompt-improver.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00128 | $0.01567 |
| Opus 5.5 | $0.00051 | $0.00627 |
| Sonnet 5.5 | $0.00026 | $0.00313 |
| Haiku 4.5 | $0.00013 | $0.00157 |
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 2mo 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.
The source is not reproduced here
No licence file
A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 2mo ago First seen · 126 lines · 128 tokens per session scan A ad9e6c5b72f2
prompt-improver is a skill published in the GitHub repository SynapSync/skills-registry (5 stars, last pushed 9d ago), with no licence file. It adds 128 tokens to every session and 1,567 once invoked, about $0.0005 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 2026-08-31.
prompt-improver compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| prompt-improverSynapSync/skills-registry | Skill | 5 | 9d ago | none | A | 128 | Claude Code |
| llm-app-patternsdavila7/claude-code-templates | Skill | 33k | yesterday | MIT | A | 54 | Claude Code, Codex |
| prompt-engineerJeffallan/claude-skills | Skill | 12k | 2d ago | MIT | A | 93 | Claude Code |
| prompt-optimizationlangwatch/langwatch | Skill | 5.0k | today | Apache-2.0 | A | 105 | Claude Code, Codex |
| prompt-library-for-startupsaws/agent-toolkit-for-aws | Skill | 3.5k | today | Apache-2.0 | A | 228 | Claude Code |
| hve-buildermicrosoft/hve-core | Skill | 1.6k | today | MIT | A | 54 | Claude Code |
| flux-txt2imgartokun/comfyui-mcp | Skill | 920 | 4d ago | MIT | A | 44 | Claude Code |