builder-kit

builder-kit is a skill for Claude Code, Codex from gabonio/agent-operator-toolkit. It costs 71 tokens per session (757 once invoked), scanned A, original, MIT.

A development workflow for planning, building, or changing software with an agent. It classifies small fixes, loads relevant guidance, protects unrelated changes, and includes checks before delivery.

In plain words
What is it for?
Use it to classify development work, inspect a repository, choose relevant technical guidance, implement small fixes, or plan larger changes from a specification.
Why use it?
It helps keep software changes focused and reviewable, especially when a task needs more planning than a quick edit.

Skill for Claude CodeCodex

Written for Claude Code and Codex: disable-model-invocation in frontmatter, but also agents/openai.yaml present.

Part of the builder-kit plugin — 5 skills shipped together

Good fit Use it to classify development work, inspect a repository, choose relevant technical guidance, implement small fixes, or plan larger changes from a specification.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/gabonio/agent-operator-toolkit/builder-kit
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 gabonio/agent-operator-toolkit --skill builder-kit
Clone the repo
git clone --depth 1 https://github.com/gabonio/agent-operator-toolkit

Made for: Claude Code, Codex.

Or install builder-kit, the plugin that ships this one along with the rest of its 5 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 builder-kit

README.md
[![agentmods](https://agentmods.dev/badge/skills/gabonio/agent-operator-toolkit/builder-kit/github.svg)](https://agentmods.dev/skills/gabonio/agent-operator-toolkit/builder-kit)
Your own site
<a href="https://agentmods.dev/skills/gabonio/agent-operator-toolkit/builder-kit"><img src="https://agentmods.dev/badge/skills/gabonio/agent-operator-toolkit/builder-kit/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 builder-kit

Your own site · 80×15
<a href="https://agentmods.dev/skills/gabonio/agent-operator-toolkit/builder-kit"><img src="https://agentmods.dev/badge/skills/gabonio/agent-operator-toolkit/builder-kit.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 71 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 757 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 $0.00071 $0.00757
Opus 5.5 $0.00028 $0.00303
Sonnet 5.5 $0.00014 $0.00151
Haiku 4.5 $0.00007 $0.00076

Measured 6d ago against content hash 8e6d80acfa47, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

builder-kit 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 6d 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/builder-kit/skills/builder-kit/SKILL.md · 43 lines

How it starts

The opening of the file, as written. The whole thing — 43 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Builder Kit

Use this skill as a router. Load only references triggered by the task.

Own the engineering discipline for the user: produce readable, maintainable software with clear capability ownership and a useful developer handoff. Do not make a non-developer choose implementation trivia or imply that invoking a skill guarantees code quality.

Start

  1. Resolve profiles and task classification.
  2. Read Git Safety, then inspect repository instructions, relevant code/tests/docs, branch, and status.
  3. Apply authority and legacy guidance.
  4. State the classification and optional lenses briefly; let the user override them.

For a tiny fix, make the smallest coherent change when implementation is requested, then use verification. For planned work, read and follow the develop-from-spec instructions and stop at its approval gate.

Conditional routing

Trigger Read or invoke
Select expert concerns lens routing, then only selected lens files
Data, APIs, search, lists, caches data boundaries
Auth, integrations, external services integration boundaries
Secrets, permissions, sensitive data security and privacy
Frontend styling or components frontend composition
Mutations, concurrency, migrations reliability and evolution
New app/modules or ownership changes domain organization and developer navigation
Language, frontend, SQL, or CI work standards routing, then only matching files
Specialized platform or service work external capability routing, then invoke an available owning skill
Prototype project prototype delivery
New application start-new-app instructions
Challenge assumptions or readiness adversarial-review instructions
Standard code/design review standard review
Repeated review of current changes PR review loop instructions
Maintaining or releasing Builder Kit release and update policy

Read the full file on GitHub · 43 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. 6d ago Changed · -5 lines 8e6d80acfa47
  2. 1mo ago First seen · 48 lines · 71 tokens per session scan A 00852fcdd199

Subscribe to this mod's changes

builder-kit is a skill published in the GitHub repository gabonio/agent-operator-toolkit (1 stars, last pushed 7d ago), licensed MIT. It adds 71 tokens to every session and 757 once invoked, about $0.0003 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.

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