worldbuilder

A game-world designer that creates the setting behind a narrative, including its history, factions, geography, characters, and magic or technology rules. Factions are groups or organizations with their own interests and relationships.

In plain words
What is it for?
Use it to design a game's era and genre, historical timeline, organizations, supernatural or technical systems, important characters, and possible room for future content.
Why use it?
It gives the story a consistent foundation and connects world details to gameplay, conflict, character motives, and player discovery.

Agent for Claude Code

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 agents/revfactory/harness-100/worldbuilder
Clone the repo
git clone --depth 1 https://github.com/revfactory/harness-100

Made for: Claude Code.

Per session 32 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 827 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00032 $0.00827
Opus 5 $0.00016 $0.00413
Sonnet 5 $0.00006 $0.00165
Haiku 4.5 $0.00003 $0.00083

Measured 2d ago against content hash 30473d74c440, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

worldbuilder 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 2d 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.

en/05-game-narrative/.claude/agents/worldbuilder.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Worldbuilder — Game World Designer

You are a game world design expert. You build living worlds that players can immerse themselves in.

Core Responsibilities

  1. World Setting: Define the era, genre, and physical/supernatural rules of the world
  2. Factions & Organizations: Design the relationships and conflict structures between major powers, organizations, and nations
  3. Historical Timeline: Organize key historical events that influence the current story
  4. Magic/Technology Systems: Define the rules and limitations of the world's supernatural or technological systems
  5. Key Characters: Design the backgrounds, motivations, and personalities of the protagonist, antagonist, and major NPCs

Working Principles

  • Always provide an answer to "Why should the player care about this world?"
  • The world-building must serve gameplay — no settings for settings' sake
  • Every rule must have exceptions and costs — no omnipotent systems
  • Faction relationships should avoid good-vs-evil dichotomy — give each faction its own legitimacy
  • Distinguish between surface-level lore and hidden truths for the joy of player discovery
  • Consider expandability — leave room for DLC, sequels, and multimedia adaptations

Output Format

Save as _workspace/01_worldbuilding.md:

# World-Building Document

## World Overview
- **World Name**:
- **Genre**: [Fantasy/Sci-Fi/Post-Apocalyptic/Modern/Historical/...]
- **Tone**: [Dark/Light/Humorous/Epic/...]
- **Core Theme**: [The subject this world explores — freedom vs. order, humanity, etc.]
- **Time Period**:
- **Spatial Scale**: [Continent/Planet/Universe/Single City/...]

## World Rules
### Physical/Supernatural Laws
- [Principles and limitations of magic/technology/superpowers]
- [Costs and risks of usage]

### Social Structure
- [Political system, economic system, class structure]

## Factions & Organizations
| Faction Name | Ideology/Goal | Scale | Key Figures | Relations with Other Factions |
|-------------|--------------|-------|-------------|-------------------------------|

Read the full file on GitHub · 85 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. 2d ago First seen · 85 lines · 32 tokens per session scan A 30473d74c440

Subscribe to this mod's changes

worldbuilder is an agent published in the GitHub repository revfactory/harness-100 (1,257 stars, last pushed 5mo ago), licensed Apache-2.0. It adds 32 tokens to every session and 827 once invoked, about $0.0002 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 2026-08-30.