ColaFlow/docs/mcp-sdk-phase3-summary.md

# MCP SDK Phase 3: Runtime Test Summary

**Date**: 2025-11-09
**Status**: ⚠️ **BLOCKED - Architecture Decision Required**

---

## TL;DR

The Microsoft MCP SDK (ModelContextProtocol v0.4.0-preview.3) is **registered in DI but NOT actually used** at runtime. ColaFlow has a custom HTTP-based MCP implementation that works independently of the SDK.

---

## Key Findings

### 🔴 Critical Issue: SDK Not Functional

```csharp
// In Program.cs - SDK is registered
builder.Services.AddMcpServer()
    .WithToolsFromAssembly()
    .WithResourcesFromAssembly();

// But custom handler is used instead
app.UseMcpMiddleware();  // <- Custom implementation, not SDK
```

**Evidence:**
- Application uses custom HTTP endpoint `/mcp` (not SDK's stdio)
- Logs show "MCP Protocol Handler initialized" (custom, not SDK)
- SDK tools (Ping, GetServerTime, GetProjectInfo) are discovered but never called
- No stdio transport (SDK's primary feature)

---

## What Works ✅

1. **Application Startup**: Starts successfully on port 5167
2. **Custom MCP Endpoint**: `/mcp` endpoint operational
3. **Resource Discovery**: 6 resources registered via custom registry
4. **API Key Auth**: Custom authentication middleware works
5. **Health Check**: `/health` endpoint returns 200 OK

---

## What Doesn't Work ❌

1. **Microsoft MCP SDK**: Not integrated with custom handler
2. **SDK stdio Transport**: Not implemented (only HTTP exists)
3. **SDK Tool Discovery**: Tools discovered but not exposed
4. **Claude Desktop Integration**: Impossible (requires stdio)
5. **Dependency Injection in SDK Tools**: Cannot verify (tools never called)

---

## Architecture Mismatch

### Expected (SDK):
```
Claude Desktop → stdio → MCP SDK → Tools/Resources
```

### Actual (Current):
```
Web Client → HTTP → Custom Handler → Custom Tools/Resources
                     (SDK ignored)
```

---

## Test Results Summary

| Component | Expected | Actual | Status |
|-----------|----------|--------|--------|
| Transport | stdio | HTTP | ❌ Mismatch |
| Endpoint | stdin/stdout | `/mcp` | ❌ Mismatch |
| Tool Discovery | SDK `.WithToolsFromAssembly()` | Custom registry | ⚠️ Partial |
| Resource Discovery | SDK `.WithResourcesFromAssembly()` | Custom registry | ✅ Works (custom) |
| Authentication | SDK built-in | Custom API Key | ✅ Works (custom) |
| DI in Tools | SDK constructor injection | N/A | ❌ Untestable |

---

## Critical Questions

### Q1: Should we use Microsoft MCP SDK at all?

**Option A: Remove SDK** (Recommended for short-term)
- ✅ Simpler architecture
- ✅ Custom implementation is working
- ❌ No Claude Desktop integration
- ❌ Non-standard MCP protocol

**Option B: Use SDK Properly** (Recommended for long-term)
- ✅ Standard MCP protocol
- ✅ Claude Desktop integration
- ❌ Requires stdio transport implementation
- ❌ More complex (hybrid approach)

**Option C: Hybrid** (Best of both worlds)
- ✅ HTTP for web clients (current)
- ✅ stdio for Claude Desktop (new)
- ✅ Shared tool/resource registry
- ❌ Most complex to implement

---

## Recommendation

### Short-term: **Option A - Remove SDK**
```csharp
// Remove from Program.cs
// builder.Services.AddMcpServer()
//     .WithToolsFromAssembly()
//     .WithResourcesFromAssembly();

// Remove from ColaFlow.API.csproj
// <PackageReference Include="ModelContextProtocol" Version="0.4.0-preview.3" />

// Keep custom implementation
app.UseMcpMiddleware();  // This works
```

**Reasoning:**
- SDK is not being used
- Custom implementation is functional
- Reduces confusion and maintenance burden
- Can re-evaluate SDK in future when it's more mature (currently preview)

### Long-term: **Option C - Hybrid**
```csharp
// Keep custom HTTP for web
app.MapPost("/mcp", CustomMcpHandler);

// Add SDK stdio for Claude Desktop
if (app.Environment.IsDevelopment())
{
    app.UseStdioMcpServer();  // <- To be implemented
}
```

**Benefits:**
- Best user experience for all clients
- Standard MCP protocol support
- Flexibility for different use cases

---

## Next Actions

1. **Decision Required**: Choose Option A, B, or C
2. **If Option A** (Remove SDK):
   - Remove NuGet package
   - Remove SDK registration
   - Update documentation
   - Continue with custom implementation
3. **If Option B/C** (Use SDK):
   - Implement stdio transport
   - Bridge SDK tools to custom handler
   - Test with Claude Desktop
   - Document both approaches

---

## Files Generated

- ✅ `docs/mcp-sdk-phase3-runtime-test-report.md` - Full detailed report
- ✅ `docs/mcp-sdk-phase3-summary.md` - This summary
- ✅ `scripts/test-mcp-runtime.ps1` - Runtime test script
- ✅ `scripts/create-test-api-key.ps1` - API key creation script

---

## Contact

For questions or decisions, please consult:
- Architect agent (architecture decisions)
- Product Manager (user requirements)
- Backend agent (implementation)

---

**Status**: Awaiting architecture decision before proceeding to Phase 4