What is worldlabs-mcp AGENTS.md?

An instruction guide for World Labs Marble, an API for generating 3D worlds, and its Spark 2.0 viewer for exploring them. It defines project entry points, response formats, transports, and testing commands.

Use it when developing, testing, or maintaining the worldlabs-mcp server, including its tool interface and local setup.

It gives an agent the project-specific rules needed to work consistently with the 3D-world service and its codebase.

How sandraschi/worldlabs-mcp configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to sandraschi/worldlabs-mcp. 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/sandraschi/worldlabs-mcp/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/sandraschi/worldlabs-mcp

Made for: Codex, OpenCode.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/sandraschi/worldlabs-mcp/agents-md/github.svg)](https://agentmods.dev/instructions/sandraschi/worldlabs-mcp/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/sandraschi/worldlabs-mcp/agents-md"><img src="https://agentmods.dev/badge/instructions/sandraschi/worldlabs-mcp/agents-md/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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/sandraschi/worldlabs-mcp/agents-md"><img src="https://agentmods.dev/badge/instructions/sandraschi/worldlabs-mcp/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 918 This file is loaded in full into every session.

When invoked 918 The same file — it is already loaded in full.

Security scan A 1 finding. 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.

Model	Per session	Once invoked
Fable 5.1	$0.00918	$0.00918
Opus 5.5	$0.00367	$0.00367
Sonnet 5.5	$0.00184	$0.00184
Haiku 4.5	$0.00092	$0.00092

Measured 22d ago against content hash 4953d6454a58, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

worldlabs-mcp AGENTS.md scanned grade A with 1 finding 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 22d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

just health # curl /health on :10865

AGENTS.md · 59 lines

How it starts

The opening of the file, as written. The whole thing — 59 lines — stays where its author put it; the contents beside it link to each section on GitHub.

worldlabs-mcp — Agent Guide

Overview

MCP server wrapping the World Labs Marble API for 3D world generation (text/image/video-to-world via Marble 1.1) and the Spark 2.0 spatial viewer. 23 MCP tools + FastAPI bridge (:10865) + webapp (:10864) + Tauri NSIS shell.

Entry Points

uv run worldlabs-mcp → worldlabs_mcp.server:main (stdio, Claude Desktop)
WORLDLABS_MCP_PORT=10865 uv run python run_server.py → HTTP on :10865 (server.py main() is stdio-only and takes no --port flag)
uv run uvicorn worldlabs_mcp.server:app --host 127.0.0.1 --port 10865 → direct ASGI
.\start.ps1 / just serve → full stack via FleetStartMode.ps1 (ports 10864/10865)

Quick Ref

uv run pytest tests/ -q          # 52 passed 8 skipped
uv run ruff check src/ --fix && uv run ruff format src/
uv run pyright src/              # 0 errors (basic mode)
just certify                     # five-gate: ruff + pyright + pytest + tsc + biome
just health                      # curl /health on :10865
just probe-llm                   # local LLM discovery
just pack                        # mcpb pack -> dist/worldlabs-mcp.mcpb

Ports

Port	Service	Config
10864	Frontend Vite (web_sota)	`fleet-start.config.ps1` FrontendPort
10865	Backend FastAPI + MCP HTTP	`fleet-start.config.ps1` BackendPort

Registered in mcp-central-docs/operations/WEBAPP_PORTS.md. Never use 3000/5000/5173/8000/8080.

Standards

FastMCP 3.4.4 >=3.4.4,<4 portmanteau pattern (tools use operation enum where >15 related)
Responses: {success, message, data} dialogic, logger.exception() in error paths, _error_response() helper
Dual transport: stdio (server:main, Claude Desktop) + HTTP (run_server.py with WORLDLABS_MCP_PORT, or direct ASGI uvicorn worldlabs_mcp.server:app)
Prefab UI: @mcp.tool(app=True) on show_worlds_card/show_world_card
Annotations: readOnlyHint/destructiveHint on all tools
Resources: world://{world_id}, gallery://{tag}; Prompts: world-gen, spark-viewer
Docs: docs/CONFIGURATION.md, DEVELOPMENT.md, TOOLS.md, TROUBLESHOOTING.md, ONBOARDING.md
See mcp-central-docs fleet standards

Read the full file on GitHub · 59 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.

22d ago Changed · +44 tokens per session 4953d6454a58
2mo ago Changed · +31 lines · +630 tokens per session a208ae4c13ff
2mo ago First seen · 28 lines · 244 tokens per session scan A b693bfcb2078

Subscribe to this mod's changes

worldlabs-mcp AGENTS.md is an instructions file published in the GitHub repository sandraschi/worldlabs-mcp (24 stars, last pushed today), licensed MIT. It adds 918 tokens to every session, about $0.0037 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

marble mcp-server webapp worldlabs

worldlabs-mcp AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
worldlabs-mcp AGENTS.mdsandraschi/worldlabs-mcp	Instructions file	24	today	MIT	A	918	Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	9,719	GitHub Copilot
next.js AGENTS.mdvercel/next.js	Instructions file	143k	today	MIT	A	7,461	Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchain	Instructions file	149k	yesterday	MIT	A	4,680	Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	5,516	GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

worldlabs-mcp: Instructions file for Codex