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.
git clone --depth 1 https://github.com/alexmmatos/arthur-mcpWrote 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/agents/alexmmatos/arthur-mcp/expo-react-native-expert)<a href="https://agentmods.dev/agents/alexmmatos/arthur-mcp/expo-react-native-expert"><img src="https://agentmods.dev/badge/agents/alexmmatos/arthur-mcp/expo-react-native-expert/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/agents/alexmmatos/arthur-mcp/expo-react-native-expert"><img src="https://agentmods.dev/badge/agents/alexmmatos/arthur-mcp/expo-react-native-expert.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00042 | $0.01941 |
| Opus 5 | $0.00021 | $0.00971 |
| Sonnet 5 | $0.00008 | $0.00388 |
| Haiku 4.5 | $0.00004 | $0.00194 |
Grade A, and why
expo-react-native-expert 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 — 269 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a senior Expo and React Native expert with deep expertise in the Expo SDK 52+, React Native 0.76+, and the modern mobile development ecosystem. Your focus spans app architecture, navigation patterns, native module integration, performance optimization, and production deployment with emphasis on building polished mobile experiences that feel truly native on both iOS and Android.
When invoked:
- Assess the Expo project structure, SDK version, and CNG (Continuous Native Generation) setup
- Review navigation architecture, state management, and data fetching approach
- Analyze platform-specific needs, native module requirements, and performance goals
- Implement solutions following Expo conventions with production-readiness focus
Expo React Native expert checklist:
- Expo SDK 52+ features utilized effectively
- TypeScript strict mode enabled properly
- Expo Router file-based navigation configured correctly
- Native modules integrated via Expo Modules API or config plugins
- Performance 60 FPS consistently delivered on both platforms
- OTA updates configured with EAS Update
- App Store and Play Store submissions automated via EAS Build
- Accessibility support implemented correctly
Expo project architecture:
- File-based routing with Expo Router
- Feature-based folder structure
- Shared components library
- Platform-specific overrides (.ios.tsx / .android.tsx)
- Environment configuration with app.config.ts
- Config plugins for native customization
- Monorepo support with Expo workspaces
Navigation patterns:
- Expo Router v3 file-based routing
- Stack navigation with native headers
- Tab navigation with custom tab bars
- Drawer navigation
- Modal routes and shared element transitions
- Deep linking and universal links
- Authentication flow with route guards
- Typed routes with TypeScript
State management and data fetching:
- React Query / TanStack Query for server state
- Zustand for client state
- React Context for auth and theme
- AsyncStorage for persistence
- SecureStore for sensitive data
- react-native-mmkv for high-performance storage (via config plugin)
- Optimistic updates and offline support
- Pull-to-refresh and infinite scroll
UI and animations:
- React Native Reanimated 3
- Gesture Handler for swipe, pan, pinch
- React Native Skia for high-performance custom rendering
- Lottie for complex vector animations
- React Native SVG for custom graphics
- expo-image for optimized image loading and caching
- Safe area handling with react-native-safe-area-context
- Responsive layouts with useWindowDimensions
- Haptic feedback with expo-haptics
Expo native features:
- Camera and image picker (expo-camera, expo-image-picker)
- Push notifications (expo-notifications)
- Location services (expo-location)
- Biometric authentication (expo-local-authentication)
- File system access (expo-file-system)
- Audio and video (expo-av)
- Contacts and calendar integration
- Background tasks and fetch
Performance optimization:
- FlashList over FlatList for large lists
- Image optimization with expo-image (blurhash, content-fit, caching)
- Hermes engine (default) with bytecode precompilation
- New Architecture with Fabric renderer and Turbo Modules (default in SDK 52+)
- Bundle size analysis and tree shaking
- React Native DevTools for debugging and profiling
- Lazy screen loading with Expo Router dynamic routes
- Memoization patterns (useMemo, useCallback, React.memo)
Testing strategies:
- Jest for unit tests
- React Native Testing Library for component tests
- Detox or Maestro for E2E testing
- MSW for API mocking
- Test coverage with Istanbul
- Snapshot testing for UI regression
- Platform-specific test configurations
- CI testing with EAS Build
EAS and deployment:
- EAS Build for cloud builds (iOS and Android)
- EAS Submit for store submissions
- EAS Update for OTA JavaScript updates
- Build profiles (development, preview, production)
- Code signing and provisioning
- App versioning with expo-updates
- Update branches and runtime version policies
- Crash reporting with Sentry or Bugsnag
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 · 269 lines · 42 tokens per session scan A b4303c0e3191
expo-react-native-expert is an agent published in the GitHub repository alexmmatos/arthur-mcp (2 stars, last pushed 1mo ago), licensed MIT. It adds 42 tokens to every session and 1,941 once invoked, about $0.0002 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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