/mcp-app-builder

name: mcp-app-builder
description: |
  Guide developers through creating and updating MCP Apps.
  Covers the full lifecycle: brainstorming ideas against UX guidelines, bootstrapping projects, implementing tools/views, debugging, running dev servers, deploying and connecting apps to ChatGPT.
  Use when a user wants to create or update a MCP App, MCP server or use the Skybridge framework.

Creating MCP Apps

Those are conversational experiences that extend AI assistants through tools and custom UI views. They're built as MCP servers invoked during conversations.

⚠️ The app is consumed by two users at once: the **human** and the **AI Assistant LLM**. They collaborate through the view—the human interacts with it, the LLM sees its state. Internalize this before writing code: the view is your shared surface.

SPEC.md keeps track of the app's requirements and design decisions. Keep it up to date as you work on the app.

**No SPEC.md?** → Read [discover.md](references/discover.md) first. Nothing else until SPEC.md exists.

**SPEC.md exists?** → Read SPEC.md, then follow [architecture.md](references/architecture.md) to design the change. Update SPEC.md, then read the relevant Implementation references below before writing code.

**Migrating from Skybridge `< 0.36.x`?** → Read [migrate-to-v1.md](references/migrate-to-v1.md) first. Users may reference `skybridge >= 0.36.x` as v1.

**Migrating from Skybridge `1.x` to `2.x`?** → Fetch the [v2.0.0 release notes](https://github.com/alpic-ai/skybridge/releases/tag/v2.0.0) first and follow them.

**Building an ecommerce app?** → Read [ecommerce.md](references/ecommerce.md) first.

Setup

1. **Copy template** → [copy-template.md](references/copy-template.md): when starting a new project with ready SPEC.md 2. **Run locally** → [run-locally.md](references/run-locally.md): when ready to test, need dev server or ChatGPT/Claude connection 3. **Evals** → [evals.md](references/evals.md): when checking that a real model reaches the right tools from natural prompts, in a test

Architecture

Design or evolve UX flows and API shape → [architecture.md](references/architecture.md)

Implementation

• **Fetch and render data** → [fetch-and-render-data.md](references/fetch-and-render-data.md): when implementing server handlers and view data fetching
• **State and context** → [state-and-context.md](references/state-and-context.md): when persisting view UI state and updating LLM context
• **Prompt LLM** → [prompt-llm.md](references/prompt-llm.md): when view needs to trigger LLM response
• **UI guidelines** → [ui-guidelines.md](references/ui-guidelines.md): display modes, layout constraints, theme, device, and locale
• **External links** → [open-external-links.md](references/open-external-links.md): when redirecting to external URLs or setting "open in app" target
• **Download file** → [download-file.md](references/download-file.md): when saving content to the user's filesystem
• **OAuth** → [oauth.md](references/oauth.md): when tools need user authentication to access user-specific data
• **CSP** → [csp.md](references/csp.md): when declaring allowed domains for fetch, assets, redirects, or iframes

Deploy

• **Ship to production** → [deploy.md](references/deploy.md): when ready to deploy via Alpic
• **Publish to ChatGPT/Claude Directories** → [publish.md](references/publish.md): when ready to submit for review

Full API docs: [https://docs.skybridge.tech/api-reference.md](https://docs.skybridge.tech/api-reference.md)

Release notes & changelog: [https://skybridge.tech/changelog.md](https://skybridge.tech/changelog.md)