# Comprehensive MCP Server Fixes for n8n Workflow Builder
## Overview
This PR contains comprehensive fixes for critical bugs in the MCP (Model Context Protocol) server that were preventing proper functionality with n8n workflow automation.
## Critical Bug Fixes
### 1. **Transport Mode Detection Issue**
- **Problem**: Server was trying to use both stdin/stdout transport and HTTP server simultaneously, causing conflicts
- **Fix**: Added smart detection between standalone HTTP mode vs MCP subprocess mode using `process.env.MCP_STANDALONE` and `process.stdin.isTTY`
- **Files**: `src/index.ts`
### 2. **Workflow Listing Bug**
- **Problem**: `workflows.filter is not a function` error due to incorrect API response parsing
- **Fix**: Corrected workflow array extraction from n8n API response structure `{data: [], nextCursor: null}`
- **Files**: `src/services/n8nApiWrapper.ts`
### 3. **API Base URL Configuration**
- **Problem**: Missing `/api/v1` path in n8n API calls
- **Fix**: Updated API base URL to include proper `/api/v1` path (`${envConfig.n8n_host}/api/v1`)
- **Files**: `src/services/environmentManager.ts`
## Workflow Execution Research & Documentation
### 4. **Workflow Execution Limitation Discovery**
- **Research**: Extensive analysis of successful executions revealed that Manual Trigger workflows are executed through n8n's web interface, not REST API
- **Evidence**: Found successful executions with `"mode": "manual"` that occurred via web interface
- **Documentation**: Added comprehensive guidance about execution limitations and alternatives
- **Files**: `src/services/n8nApiWrapper.ts`
### 5. **Improved User Experience**
- **Enhancement**: Replaced failed API attempts with helpful guidance
- **Features**:
- Clear explanation of n8n design limitations
- Step-by-step execution instructions
- Alternative trigger type recommendations
- Comprehensive error handling
## Testing Results
### ✅ Working MCP Tools
- `list_workflows`: Returns all workflows correctly
- `get_workflow`: Returns detailed workflow information
- `create_workflow`: Creates workflows via MCP
- `update_workflow`: Updates workflows via MCP
- `list_executions`: Shows existing executions
- `get_execution`: Returns execution details
### ✅ CFP Automation Workflows
- Successfully imported 3 sophisticated CFP scraping workflows
- Enhanced workflow with Google Gemini AI integration working
- Workflows can be managed programmatically via MCP tools
- Manual execution confirmed working via n8n web interface
## Impact
- **Before**: MCP server completely non-functional due to transport conflicts and API parsing errors
- **After**: Fully functional MCP server with comprehensive workflow management capabilities
- **Benefit**: Enables AI-powered CFP automation with programmatic workflow control
## Files Changed
- `src/index.ts` - Transport mode detection
- `src/services/n8nApiWrapper.ts` - API parsing fixes and execution guidance
- `src/services/environmentManager.ts` - Base URL configuration
## Breaking Changes
None - all changes are backwards compatible improvements and bug fixes.
## Additional Notes
- All changes have been thoroughly tested with real n8n instance
- Workflow execution limitation is a design choice by n8n, not a bug in our implementation
- Users can still execute workflows manually via n8n web interface
- Alternative trigger types (webhooks, schedules) support API-based execution
