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storyden: Skill for Claude Code

.agents/skills/agent-builder/SKILL.md

agent-builder is a skill for Claude Code, Codex from Southclaws/storyden. It costs 40 tokens per session (990 once invoked), scanned A, original, MPL-2.0.

A design aid for improving the placement, spacing, grouping, and visual order of elements on a page or screen.

In plain words
What is it for?
Use it to review grids, adjust margins and padding, group related elements, create visual rhythm, and strengthen the hierarchy of a page.
Why use it?
It helps fix layouts that feel crowded, repetitive, randomly spaced, or difficult to scan by creating clearer relationships between related and unrelated content.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

This is Southclaws/storyden's own configuration. It tells Claude Code and Codex how to work on storyden itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything storyden configures →

not rated 346repo +1 3d ago A scan SkillSpector: pass 40 tokens original MPL-2.0
View source ↗ Southclaws/storyden storyden.org
Reuse

Borrowing it

Nothing to install: this file belongs to Southclaws/storyden. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/Southclaws/storyden/main/.agents/skills/agent-builder/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/Southclaws/storyden

Made for: Claude Code, Codex.

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 agent-builder

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/southclaws/storyden/agent-builder"><img src="https://agentmods.dev/badge/skills/southclaws/storyden/agent-builder.svg" alt="Reviewed on agentmods" width="80" 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 990 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00040 $0.00990
Opus 5.5 $0.00016 $0.00396
Sonnet 5.5 $0.00008 $0.00198
Haiku 4.5 $0.00004 $0.00099

Measured 2mo ago against content hash 7f84ab0b9a4f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

agent-builder 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.

.agents/skills/agent-builder/SKILL.md · 119 lines

How it starts

The opening of the file, as written. The whole thing — 119 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Storyden Agent Builder

Use this skill when creating or improving a built-in Storyden Robot, its playbook, tool descriptions, tool schemas, or tool result shapes.

Built-in Storyden Robots run inside the Storyden ADK integration. They should be self-contained: do not require runtime web access, external skills, or documents unless a configured tool explicitly provides that capability.

Core Workflow

  1. Define the Robot's job.

    • State what user outcomes it owns.
    • State what it must not attempt.
    • Keep the scope narrow enough that the available tools can finish the workflow.

  2. Map the workflow to tools.

    • Prefer a few focused tools over many overlapping tools.
    • Treat tool names, descriptions, inputs, outputs, and side effects as part of the Robot prompt.
    • Move deterministic minutia into tools instead of telling the Robot to remember it.

  3. Shape tool responses.

    • Return high-signal fields in domain language.
    • Include enough context for the next action.
    • Add message and next_action fields when the result should steer the Robot.
    • Hide implementation trivia unless it changes what the Robot should do.
    • Make errors actionable and specific.

  4. Write the playbook.

    • Define stages: discover, plan, edit/act, validate, deliver.
    • Define when to ask versus act.
    • Define authoritative tools for facts and side effects.
    • Define failure behavior and user-facing language.
    • Keep external references distilled locally; runtime Robots may be network-restricted.

  5. Add eval scenarios.

    • Use realistic tasks with multi-step workflows.
    • Include failure cases and repeated attempts.
    • Verify both final outcome and tool path when tool choice matters.
    • Review raw transcripts, not just final summaries.

Good Robot Instructions

Good instructions:

  • Define the Robot's job in one concrete paragraph.
  • Define boundaries and forbidden behavior.
  • Define workflow stages in the order tools should normally be used.
  • Explain when to ask a user versus making a reasonable choice.
  • Tie tool names to domain jobs, not internal implementation details.
  • Define what success looks like.
  • Define failure behavior in user-facing language.
  • Keep the Robot from seeing implementation distractions that tools can handle.

Read the full file on GitHub · 119 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.

  1. 2mo ago First seen · 119 lines · 40 tokens per session scan A 7f84ab0b9a4f

Subscribe to this mod's changes

agent-builder is a skill published in the GitHub repository Southclaws/storyden (346 stars, last pushed 3d ago), licensed MPL-2.0. It adds 40 tokens to every session and 990 once invoked, about $0.0002 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 2026-08-30.

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Related

agent-builder compared with skills from other repositories

agent-builder next to 6 skills from other repositories
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html-ppt-hermes-cyber-terminalnexu-io/open-designSkill106kyesterdayApache-2.0A53Claude Code, Codex
html-ppt-taste-brutalistnexu-io/open-designSkill106kyesterdayApache-2.0A78Claude Code, Codex
visual-ralphYeachan-Heo/oh-my-codexSkill34k3d agoMITA52Codex
glance-canonical-layoutsandroid/skillsSkill10kyesterdayApache-2.0A56Claude Code
accessibilitymicrosoft/hve-coreSkill1.6kyesterdayMITA47Claude Code