What is chatgpt-apps?

A guide for building ChatGPT Apps SDK applications that connect an MCP server to an interactive widget. MCP is a standard way for an app to expose tools and data to an AI assistant.

It helps plan tools, register resources, create MCP handlers and widget interfaces, and validate local setup against current OpenAI documentation.

It helps resolve the server, widget, metadata, security, and compatibility details needed for an app to work inside ChatGPT.

chatgpt-apps — Skill for Claude Code and Codex by tercumantanumut

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 tercumantanumut/selene --skill chatgpt-apps

Clone the repo

git clone --depth 1 https://github.com/tercumantanumut/selene

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/tercumantanumut/selene/chatgpt-apps/github.svg)](https://agentmods.dev/skills/tercumantanumut/selene/chatgpt-apps)

Your own site

<a href="https://agentmods.dev/skills/tercumantanumut/selene/chatgpt-apps"><img src="https://agentmods.dev/badge/skills/tercumantanumut/selene/chatgpt-apps/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/skills/tercumantanumut/selene/chatgpt-apps"><img src="https://agentmods.dev/badge/skills/tercumantanumut/selene/chatgpt-apps.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 96 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 4,325 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 warn 7 Sept 2026

SkillSpector: 1 finding, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

high Prompt Injection · line 252
This pattern attempts to override system instructions or ignore safety constraints. Without LLM analysis, manual review is recommended.

Fix: Remove or rewrite any text that instructs the agent to ignore prompts, override safety rules, or trust unverified content. Ensure skill content cannot be injected to alter agent behavior.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00096	$0.04325
Opus 5	$0.00048	$0.02162
Sonnet 5	$0.00019	$0.00865
Haiku 4.5	$0.00010	$0.00432

Measured 11d ago against content hash 9af2095eb549, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

chatgpt-apps 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.

lib/skills/catalog/bundled/chatgpt-apps/SKILL.md · 321 lines

How it starts

The opening of the file, as written. The whole thing — 321 lines — stays where its author put it; the contents beside it link to each section on GitHub.

ChatGPT Apps

Overview

Scaffold ChatGPT Apps SDK implementations with a docs-first, example-first workflow, then generate code that follows current Apps SDK and MCP Apps bridge patterns.

Use this skill to produce:

A primary app-archetype classification and repo-shape decision
A tool plan (names, schemas, annotations, outputs)
An upstream starting-point recommendation (official example, ext-apps example, or local fallback scaffold)
An MCP server scaffold (resource registration, tool handlers, metadata)
A widget scaffold (MCP Apps bridge first, window.openai compatibility/extensions second)
A reusable Node + @modelcontextprotocol/ext-apps starter scaffold for low-dependency fallbacks
A validation report against the minimum working repo contract
Local dev and connector setup steps
A short stakeholder summary of what the app does (when requested)

Mandatory Docs-First Workflow

Use $openai-docs first whenever building or changing a ChatGPT Apps SDK app.

Invoke $openai-docs (preferred) or call the OpenAI docs MCP server directly.
Fetch current Apps SDK docs before writing code, especially (baselene pages):
- apps-sdk/build/mcp-server
- apps-sdk/build/chatgpt-ui
- apps-sdk/build/examples
- apps-sdk/plan/tools
- apps-sdk/reference
Fetch apps-sdk/quickstart when scaffolding a new app or generating a first-pass implementation, and check the official examples repo/page before inventing a scaffold from scratch.
Fetch deployment/submission docs when the task includes local ChatGPT testing, hosting, or public launch:
- apps-sdk/deploy
- apps-sdk/deploy/submission
- apps-sdk/app-submission-guidelines
Cite the docs URLs you used when explaining design choices or generated scaffolds.
Prefer current docs guidance over older repo patterns when they differ, and call out compatibility aliases explicitly.
If doc search times out or returns poor matches, fetch the canonical Apps SDK pages directly by URL and continue; do not let search failure block scaffolding.

Read the full file on GitHub · 321 lines

Files

What ships with it

7 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.

11d ago First seen · 321 lines · 96 tokens per session scan A 9af2095eb549

Subscribe to this mod's changes

chatgpt-apps is a skill published in the GitHub repository tercumantanumut/selene (168 stars, last pushed 1mo ago), licensed MIT. It adds 96 tokens to every session and 4,325 once invoked, about $0.0005 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.

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