at-simplify

at-simplify is a skill for Claude Code, Codex from kairyou/agent-tools. It costs 40 tokens per session (675 once invoked), scanned A, a copy of simplify, MIT.

A code-cleanup tool that reviews changed code and reduces duplication, complexity, and unnecessary work.

In plain words
What is it for?
Use it on diffs, commit ranges, pull requests, file paths, staged changes, or uncommitted working-tree changes.
Why use it?
It helps make recent changes easier to maintain without mixing cleanup with bug hunting.

Skill for Claude CodeCodex

Part of the agent-tools plugin — 8 skills shipped together

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.

agentmods
npx agentmods add skills/kairyou/agent-tools/at-simplify
Any agent
npx skills add kairyou/agent-tools --skill at-simplify
Clone the repo
git clone --depth 1 https://github.com/kairyou/agent-tools

Made for: Claude Code, Codex.

Or install agent-tools, the plugin that ships this one along with the rest of its 8 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 at-simplify

README.md
[![agentmods](https://agentmods.dev/badge/skills/kairyou/agent-tools/at-simplify.svg)](https://agentmods.dev/skills/kairyou/agent-tools/at-simplify)
Your own site
<a href="https://agentmods.dev/skills/kairyou/agent-tools/at-simplify"><img src="https://agentmods.dev/badge/skills/kairyou/agent-tools/at-simplify.svg" alt="Measured on agentmods" height="20"></a>
Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 675 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 89% copy Near-identical to another mod 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 $0.00040 $0.00675
Opus 5 $0.00020 $0.00338
Sonnet 5 $0.00008 $0.00135
Haiku 4.5 $0.00004 $0.00068

Measured 5d ago against content hash b4c7cb831d95, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

at-simplify 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 5d 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.

Origin

This is a copy

89% identical to simplify — 16 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/workflow/at-simplify/SKILL.md · 69 lines

How it starts

The opening of the file, as written. The whole thing — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Simplify

at-simplify → 4 cleanup agents in parallel → apply the fixes

You are improving the quality of the changed code, not hunting for bugs. Review it for reuse, simplification, efficiency, and altitude issues, then fix what you find. Do not look for correctness bugs — that is what at-review is for.

Phase 0 — Gather the diff

Run git diff "@{upstream}...HEAD" (or git diff main...HEAD / git diff HEAD~1 if there's no upstream) to get the unified diff under review. If there are uncommitted changes, or the range diff is empty, also run git diff HEAD and include the working-tree changes in scope — the review often runs before the commit. If a PR number, branch name, or file path was passed as an argument, review that target instead. Treat this diff as the review scope.

Phase 1 — Review (4 cleanup agents in parallel)

Launch 4 independent review agents using multi-agent capabilities, all in a single message so they run concurrently. Pass each agent the diff and one of the four angles below. Each returns its findings with file, line, a one-line summary, and the concrete cost (what is duplicated, wasted, or harder to maintain).

Reuse

Flag new code that re-implements something the codebase already has — Grep shared/utility modules and files adjacent to the change, and name the existing helper to call instead.

Simplification

Flag unnecessary complexity the diff adds: redundant or derivable state, copy-paste with slight variation, deep nesting, dead code left behind. Name the simpler form that does the same job.

Efficiency

Flag wasted work the diff introduces: redundant computation or repeated I/O, independent operations run sequentially, blocking work added to startup or hot paths. Also flag long-lived objects built from closures or captured environments — they keep the entire enclosing scope alive for the object's lifetime (a memory leak when that scope holds large values); prefer a class/struct that copies only the fields it needs. Name the cheaper alternative.

Read the full file on GitHub · 69 lines

Files

What ships with it

1 file 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.

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. 5d ago First seen · 69 lines · 40 tokens per session scan A b4c7cb831d95

Subscribe to this mod's changes

at-simplify is a skill published in the GitHub repository kairyou/agent-tools (177 stars, last pushed 4d ago), licensed MIT. It adds 40 tokens to every session and 675 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to simplify, differing in 16 lines, and is treated as a copy.