ControlAPI-MCP v0.3.2 - Content-Type Visibility & Critical Bugfix

🐛 Critical Bug Fixed

Server Configuration Failure from Initial State

Issue: When starting fresh (no server configured yet), attempting to connect to a server would fail with:

Error: Request URL is missing an 'http://' or 'https://' protocol.

Root Cause: When set_server_config fails to load a new schema, it attempts to restore the previous server configuration by calling loader.reload_with_url(temp_loader_url). However, on first run when no server is configured, temp_loader_url is "not-configured" (a placeholder string, not a valid URL). This caused httpx to fail when trying to fetch the schema.

Fix: Check if the previous URL is valid (temp_loader_url != "not-configured") before attempting to reload it. If starting fresh and the new server fails to load, simply don't attempt a rollback.

File changed: src/tools.py (line 309)

✨ New Features

1. Content-Type Visibility in Endpoint Listings

Endpoint listings now show which content-types each endpoint accepts, making it clear when endpoints require special encoding:

{
  "path": "/api/v1/auth/login",
  "method": "POST",
  "summary": "Login",
  "content_types": ["application/x-www-form-urlencoded"]
}

Benefits:

• AI agents can see content-type requirements at a glance
• Easier debugging of API integration issues
• Clear documentation of endpoint expectations

Files changed:

• src/openapi_loader.py - Added content_types field to Endpoint dataclass
• src/tools.py - Updated list_endpoints and search_schema to include content-types

2. New Tool: get_endpoint_details

Get comprehensive schema information for any endpoint:

{
  "path": "/api/v1/auth/login",
  "method": "POST",
  "summary": "Login",
  "description": "Login user and return tokens with user data.",
  "content_types": ["application/x-www-form-urlencoded"],
  "request_body_required": true,
  "request_schemas": {
    "application/x-www-form-urlencoded": {
      "$ref": "#/components/schemas/Body_login_api_v1_auth_login_post"
    }
  },
  "parameters": [...]
}

Features:

• Shows all accepted content-types
• Indicates if request body is required
• Provides full request schema for each content-type
• Lists all parameters (path, query, header)

File changed: src/tools.py - Added new tool handler

3. Content-Type Auto-Detection (Enhanced Visibility)

Auto-detection was implemented in v0.3.0 but wasn't visible to AI agents. Now the schema information is exposed, making it clear:

• Auto-sets Content-Type from OpenAPI schema when not provided
• Preserves user-specified Content-Type headers
• Works transparently - no manual header configuration needed

How it works:

1. openapi_loader.get_preferred_content_type() extracts content-type from schema
2. Priority: application/x-www-form-urlencoded > application/json > first available
3. Auto-sets header only if: endpoint has body AND user hasn't specified Content-Type
4. Uses httpx data= for form encoding, json= for JSON

🔧 Technical Details

Modified Files:

• src/openapi_loader.py - Extract and expose content-types from schemas
• src/tools.py - Add endpoint details tool, expose content-types in listings, fix rollback bug
• src/main.py - Add debugpy remote debugging support (optional, via MCP_DEBUG=1 env var)

New Files:

• .vscode/launch.json - Debugger configuration for MCP server

📋 Test Results

✅ Initial server setup: Connects successfully from unconfigured state
✅ Content-type visibility: Login endpoint shows application/x-www-form-urlencoded
✅ Auto-detection: Login works without manual Content-Type header
✅ User override: Explicit Content-Type headers are preserved
✅ GET requests: No Content-Type set when body is empty
✅ Detailed inspection: get_endpoint_details returns complete schema info

🎯 Impact

Before this release:

• ❌ Could not configure server on first run
• ❌ Content-type requirements hidden from AI agents
• ❌ No way to inspect detailed endpoint schemas
• ❌ Auto-detection worked but wasn't documented/visible

After this release:

• ✅ Server configuration works seamlessly from fresh start
• ✅ Content-types visible in all endpoint listings
• ✅ Dedicated tool for detailed schema inspection
• ✅ Complete transparency of auto-detection behavior

🛠️ Development Tools Added

Remote Debugging Support:

• Set MCP_DEBUG=1 environment variable in mcp.json
• Debugger listens on localhost:5678
• Use "Attach to MCP Server" launch configuration
• Helpful for troubleshooting complex MCP interactions

🙏 Acknowledgments

Thanks to the debugging session that uncovered the server configuration bug and led to improved content-type visibility!