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.
npx skills add pproenca/dot-skills --skill chat-apps-ui-sdkgit clone --depth 1 https://github.com/pproenca/dot-skillsWrote 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.
[](https://agentmods.dev/skills/pproenca/dot-skills/chat-apps-ui-sdk)<a href="https://agentmods.dev/skills/pproenca/dot-skills/chat-apps-ui-sdk"><img src="https://agentmods.dev/badge/skills/pproenca/dot-skills/chat-apps-ui-sdk/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.
<a href="https://agentmods.dev/skills/pproenca/dot-skills/chat-apps-ui-sdk"><img src="https://agentmods.dev/badge/skills/pproenca/dot-skills/chat-apps-ui-sdk.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00148 | $0.02282 |
| Opus 5 | $0.00074 | $0.01141 |
| Sonnet 5 | $0.00030 | $0.00456 |
| Haiku 4.5 | $0.00015 | $0.00228 |
Grade A, and why
chat-apps-ui-sdk 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 5d 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.
How it starts
The opening of the file, as written. The whole thing — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Chat Apps UI SDK Best Practices
A reference for building beautiful, review-ready apps that render interactive UI inside the chat surface of ChatGPT and Claude. As of January 2026 these platforms share one foundation — the MCP Apps standard (@modelcontextprotocol/ext-apps), rendered by Claude, ChatGPT, VS Code, and Goose. The OpenAI Apps SDK is a superset adding the window.openai bridge, and MCP-UI (@mcp-ui/server / @mcp-ui/client) is the community implementation. This skill contains 46 rules across 8 categories, ordered by impact so the highest-leverage decisions come first.
The mental model: an app is an MCP tool first, UI second. The model invokes a tool; the tool returns data plus a link to a UI resource; the host renders that resource in a sandboxed iframe; the iframe talks back over a defined bridge. Mistakes early in that chain mean nothing renders; mistakes later mean it renders broken, unsafe, or unpolished.
When to Apply
Reference these guidelines when:
- Designing the MCP tool and
structuredContent/content/_metacontract for a chat app - Wiring a tool to a component (
_meta.ui.resourceUri, thetext/html;profile=mcp-appMIME type, theui://scheme) - Writing the iframe component and its bridge (
window.openai,ui/notifications/*, MCP-UIonUIAction) - Choosing display modes, widget state, theming, and responsive layout
- Hardening a chat app (CSP, sandbox, secrets, OAuth) or preparing it for directory submission
- Reviewing or refactoring existing ChatGPT-app / Claude-app / MCP-UI code
Rule Categories by Priority
| Priority | Category | Impact | Prefix |
|---|---|---|---|
| 1 | MCP Tool & Discovery Design | CRITICAL | tool- |
| 2 | UI Resource Wiring & Templates | CRITICAL | wire- |
| 3 | Host–Component Data Bridge | HIGH | bridge- |
| 4 | Display Modes & Responsive Layout | HIGH | display- |
| 5 | State & Model Context | HIGH | state- |
| 6 | Security & Data Boundaries | HIGH | sec- |
| 7 | Visual Design & UX Polish | MEDIUM-HIGH | design- |
| 8 | Distribution & Cross-Host Portability | MEDIUM | dist- |
What ships with it
50 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.
- AGENTS.md 11 KB
- assets/templates/_template.md 1.6 KB
- metadata.json 1.9 KB
- references/_sections.md 4.1 KB
- references/bridge-call-tools-app-visibility.md 1.5 KB
- references/bridge-followup-vs-silent-call.md 1.4 KB
- references/bridge-handle-all-mcpui-actions.md 1.3 KB
- references/bridge-render-from-notifications.md 1.5 KB
- references/bridge-use-host-apis.md 1.4 KB
- references/bridge-validate-postmessage-origin.md 1.3 KB
- references/design-inherit-native-typography.md 1.1 KB
- references/design-limit-actions-hierarchy.md 1.1 KB
- references/design-meet-wcag-contrast.md 1.1 KB
- references/design-render-loading-empty-error.md 1.2 KB
- references/design-respect-reduced-motion.md 1016 B
- references/design-restrain-brand-color.md 1.1 KB
- references/display-avoid-nested-scroll.md 1.1 KB
- references/display-pick-the-right-mode.md 1.2 KB
- references/display-report-intrinsic-height.md 1.3 KB
- references/display-request-mode-with-fallback.md 1.2 KB
- references/display-respect-theme.md 1.3 KB
- references/display-responsive-breakpoints.md 1.1 KB
- references/dist-build-on-mcp-apps-standard.md 1.3 KB
- references/dist-degrade-without-ui.md 1.2 KB
- references/dist-feature-detect-host-apis.md 1.1 KB
- references/dist-provide-submission-metadata.md 1.2 KB
- references/sec-avoid-frame-domains.md 1.3 KB
- references/sec-declare-csp-allowlist.md 1.3 KB
- references/sec-enforce-server-side-auth.md 1.1 KB
- references/sec-minimize-restricted-data.md 1.2 KB
- references/sec-no-secrets-in-payloads.md 1.3 KB
- references/sec-signal-oauth-challenge.md 1.3 KB
- references/state-keep-state-small.md 1.0 KB
- references/state-no-secrets-in-state.md 1.1 KB
- references/state-persist-widget-state.md 1.3 KB
- references/state-separate-three-stores.md 1.6 KB
- references/state-update-model-context.md 1.3 KB
- references/tool-feed-widget-in-response.md 1.4 KB
- references/tool-honest-descriptions.md 1.4 KB
- references/tool-minimal-scoped-inputs.md 1.3 KB
- references/tool-output-schema-validation.md 1.6 KB
- references/tool-safety-annotations.md 1.4 KB
- references/tool-specific-verb-names.md 1.3 KB
- references/tool-structured-content-contract.md 1.7 KB
- references/wire-inline-self-contained-bundle.md 1.5 KB
- references/wire-mcp-app-mimetype.md 1.2 KB
- references/wire-resource-uri-link.md 1.4 KB
- references/wire-set-ui-domain.md 1.3 KB
- references/wire-ui-scheme-and-handler.md 1.3 KB
- references/wire-version-uri-cache-key.md 1.2 KB
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.
- 5d ago First seen · 125 lines · 148 tokens per session scan A db2646ff0cc5
chat-apps-ui-sdk is a skill published in the GitHub repository pproenca/dot-skills (205 stars, last pushed 24d ago), licensed MIT. It adds 148 tokens to every session and 2,282 once invoked, about $0.0007 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 2026-09-03.
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