mcp-app-verification
Comprehensive verification checklists for MCP Apps. Tests with basic-host reference, validates handler-before-connect, text fallback, resource URI linking, single-file bundling, host styling, CSP, and legacy pattern detection.
npx skills add a5c-ai/babysitter --skill mcp-app-verification --agent claude-code
Same command for any agent — swap --agent for codex, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# mcp-app-verification Run comprehensive verification checklists for MCP Apps covering correctness, compatibility, and migration completeness. ## Overview MCP Apps have several critical invariants that must be verified before deployment. This skill provides systematic verification across multiple dimensions: 1. **Runtime verification**: App loads and functions in basic-host reference 2. **Pattern verification**: Critical code patterns are correct (handler-before-connect, text fallback) 3. **Build verification**: Single-file bundle is valid and complete 4. **Styling verification**: Host theming applies correctly 5. **CSP verification**: All origins declared, no silent failures 6. **Migration verification**: No remaining legacy patterns (OpenAI, old MIME types, snake_case) ## Capabilities ### basic-host Test Execution - Build the MCP App - Start the server - Launch basic-host reference implementation against the server - Verify app loads without console errors - Verify handlers fire correctly ### Handler-Before-Connect Invariant - Search source code for `app.connect()` call - Verify ALL handlers (`ontoolinput`, `ontoolresult`, `onhostcontextchanged`, `onteardown`) are registered BEFO
- Overview
- Capabilities
- basic-host Test Execution
- Handler-Before-Connect Invariant
- Text Fallback Verification
- Resource URI Link Integrity
- Single-File Bundle Verification
- Host Styling Verification
- CSP Verification
- Legacy Pattern Detection (Migration)
- Usage
- Full Verification Workflow
- Pattern Verification Commands
- Migration Verification (OpenAI -> MCP)
Step 1: Build the project npm run build Step 2: Verify single-file bundle ls -la dist/mcp-app.html Should be a single file with all assets inlined Step 3: Check for external references in bundle grep -E '<script src="|<link.*href="|<img src="(?!data:)' dist/mcp-app.html Should return NOTHING (all assets inlined) Step 4: Start server npm run serve &
What does the mcp-app-verification skill do?
Comprehensive verification checklists for MCP Apps. Tests with basic-host reference, validates handler-before-connect, text fallback, resource URI linking, single-file bundling, host styling, CSP, and legacy pattern detection.
How do I install it?
Run `npx skills add a5c-ai/babysitter --skill mcp-app-verification --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From a5c-ai/babysitter, a repository with 1,642 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.