worldbuilding

worldbuilding is a skill for Claude Code, Codex from bs779517/story-skills. It costs 71 tokens per session (653 once invoked), scanned A, original, MIT.

A guide for creating and managing the places, cultures, histories, and systems that make up a story world.

In plain words
What is it for?
Use it when adding locations, magic, politics, technology, religion, economies, cultures, or world history to an existing story project.
Why use it?
It keeps world details organized in linked files and grounded in the existing story's genre, era, and tone.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it when adding locations, magic, politics, technology, religion, economies, cultures, or world history to an existing story project.

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Install with agentmods
npx agentmods add skills/bs779517/story-skills/worldbuilding
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 bs779517/story-skills --skill worldbuilding
Clone the repo
git clone --depth 1 https://github.com/bs779517/story-skills

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 worldbuilding

README.md
[![agentmods](https://agentmods.dev/badge/skills/bs779517/story-skills/worldbuilding/github.svg)](https://agentmods.dev/skills/bs779517/story-skills/worldbuilding)
Your own site
<a href="https://agentmods.dev/skills/bs779517/story-skills/worldbuilding"><img src="https://agentmods.dev/badge/skills/bs779517/story-skills/worldbuilding/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 worldbuilding

Your own site · 80×15
<a href="https://agentmods.dev/skills/bs779517/story-skills/worldbuilding"><img src="https://agentmods.dev/badge/skills/bs779517/story-skills/worldbuilding.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 653 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 $0.00653
Opus 5 $0.00036 $0.00327
Sonnet 5 $0.00014 $0.00131
Haiku 4.5 $0.00007 $0.00065

Measured 11d ago against content hash fc8643293015, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

worldbuilding 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 11d 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.

skills/worldbuilding/SKILL.md · 62 lines

How it starts

The opening of the file, as written. The whole thing — 62 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Worldbuilding

Overview

Create and manage world elements for a story project. Locations and systems (magic, politics, technology, etc.) are stored as markdown files in the worldbuilding/ directory with YAML frontmatter. All elements cross-reference characters and other story elements.

Prerequisites

A story project must already exist (created via the story-init skill). Verify by checking for story.md in the project root.

Creating a Location

  1. Read story.md for genre, era, and tone context
  2. Read worldbuilding/_index.md for existing locations and systems
  3. Ask for the location's name and type (city, fortress, wilderness, etc.)
  4. Build the location through conversation, covering:
    • Physical description and atmosphere
    • History relevant to the story
    • Culture and customs of inhabitants
    • Notable features characters will interact with
    • Current state at story's timeline
  5. Write the file using references/location-template.md
  6. Save to worldbuilding/locations/{name-kebab}.md
  7. Update worldbuilding/_index.md locations table
  8. If notable characters are listed, verify those character files exist and add location references to them

Creating a System

  1. Read story.md for genre and themes context
  2. Read worldbuilding/_index.md for existing systems
  3. Identify the system type and consult references/world-element-types.md for the relevant prompts
  4. Build the system through conversation, addressing the key questions for that type
  5. Write the file using references/system-template.md
  6. Save to worldbuilding/systems/{name-kebab}.md
  7. Update worldbuilding/_index.md systems table
  8. Cross-reference with characters who interact with the system (e.g., magic-users for a magic system)

Updating World Elements

  1. Read the existing file
  2. Make the requested changes
  3. If cross-references changed, update the linked files
  4. Update worldbuilding/_index.md if name, type, or status changed

Cross-Referencing

  • Locations reference characters via notable-characters in frontmatter
  • Systems reference practitioners via character tags
  • When a location is used in a chapter, the chapter's frontmatter locations field links back
  • Keep the worldbuilding/_index.md world overview section current as elements are added

Read the full file on GitHub · 62 lines

Files

What ships with it

4 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.

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. 11d ago First seen · 62 lines · 71 tokens per session scan A fc8643293015

Subscribe to this mod's changes

worldbuilding is a skill published in the GitHub repository bs779517/story-skills (8 stars, last pushed today), licensed MIT. It adds 71 tokens to every session and 653 once invoked, about $0.0004 per session on Opus 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.