# ⚠️ Vercel Serverless Limitations
## The Problem
Your API is getting `500: INTERNAL_SERVER_ERROR` / `FUNCTION_INVOCATION_FAILED` because:
### Vercel Serverless Functions Limitations:
1. **❌ No Subprocess Support**
- Your MCP server runs as a subprocess
- Vercel serverless functions don't support subprocess execution
- This is a fundamental limitation
2. **❌ Limited File System Access**
- RAG docs, domain configs, schemas need file system access
- Serverless functions have read-only `/tmp` access
- Your files may not be accessible
3. **❌ Execution Time Limits**
- Free tier: 10 seconds max
- Pro tier: 60 seconds max
- Reasoning queries can take longer
4. **❌ Cold Starts**
- First request is slow (3-5 seconds)
- Each function invocation is isolated
---
## ✅ Solution: Use Render or Railway Instead
**Vercel is NOT suitable for this application** because:
- It requires subprocess execution (MCP server)
- It needs persistent file system access
- It needs longer execution times
**Better alternatives:**
- ✅ **Render.com** - Full Python support, subprocess allowed
- ✅ **Railway.app** - Docker-like environment, everything works
- ✅ **Fly.io** - Good for Python apps
---
## 🚀 Quick Migration to Render (Recommended)
### Step 1: Sign Up on Render
1. Go to [render.com](https://render.com)
2. Sign up (free account)
### Step 2: Deploy Backend
1. **New** → **Web Service**
2. **Connect GitHub** (or upload code)
3. **Settings:**
```
Name: mcp-reasoning-engine
Environment: Python 3
Build Command: pip install -r requirements.txt
Start Command: uvicorn app:app --host 0.0.0.0 --port $PORT
```
4. **Environment Variables:**
- `ANTHROPIC_API_KEY` = your_key_here
5. **Deploy!**
### Step 3: Deploy Frontend on Vercel
- Keep frontend on Vercel (static files work fine!)
- Update `public/index.html` API URL to Render URL
- ✅ Best of both worlds!
---
## 🎯 Why This Will Work
**Render:**
- ✅ Full Python runtime (not serverless)
- ✅ Subprocess execution supported
- ✅ Full file system access
- ✅ No execution time limits (within reason)
- ✅ Free tier available
**Vercel (for frontend only):**
- ✅ Perfect for static HTML/CSS/JS
- ✅ Fast CDN delivery
- ✅ No server needed
---
## 📋 Migration Checklist
- [ ] Sign up on Render
- [ ] Create web service
- [ ] Add `ANTHROPIC_API_KEY` environment variable
- [ ] Deploy backend
- [ ] Test Render API URL
- [ ] Update `public/index.html` with Render URL
- [ ] Redeploy frontend on Vercel
- [ ] ✅ Everything works!
---
## 🔄 Current Status
**Your Vercel deployment:**
- ❌ Backend failing (serverless limitations)
- ✅ Frontend can stay on Vercel (it's just HTML)
**Recommended setup:**
- ✅ Backend → Render (full Python support)
- ✅ Frontend → Vercel (static files)
- ✅ Best performance and reliability
---
**The MCP server needs a real Python environment, not serverless. Render/Railway will solve this! 🚀**
