Adding an MCP Server for Agentforce Agent Client

  I'm trying to register a custom MCP (Model Context Protocol) server with Agentforce Registry as an External Service, but getting this error: 

  We couldn't connect to the MCP server. Check the Server URL and try again. 

  API Catalog Error fetching server definition APPX: Exception occurred while retrieving service descriptor, ExternalServiceException:errorFetchMcpServerDefinition 

  However, my server logs show all requests are succeeding: 

  - GET /mcp/http → 200 OK (returns server discovery metadata) 

  - POST /oauth2/token → 201 Created (returns access token) 

  - POST /mcp/http (initialize) → 201 Created (MCP initialize handshake) 

  - POST /mcp/http (notifications/initialized) → 201 Created 

  The server correctly implements: 

  - OAuth 2.0 Client Credentials flow 

  - MCP HTTP transport with JSON-RPC 2.0 

  - Server discovery endpoint returning protocol version 2025-06-18 

  Questions: 

  1. Are there additional requirements for MCP server registration beyond successful API calls? 

  2. Does ExternalServiceException:errorFetchMcpServerDefinition indicate a specific validation failure? 

  3. Are there logs or debugging tools in Salesforce to see why registration fails after successful connection? 

  4. Is there a specific response format or schema the API Catalog expects that might not be documented? 

  Any guidance would be appreciated!