Azure MCP Server Returns Non-JSON-RPC Format, Breaking Docker MCP Gateway

[NotMyself]

Summary

The Azure MCP server returns a custom JSON response format instead of JSON-RPC 2.0, causing all tool calls through Docker MCP gateway to fail with invalid character 'S' looking for beginning of value.

Full Bug Report

See detailed analysis and reproduction steps at:
NotMyself/claude-hall-monitor#1

Quick Summary

• Azure MCP returns {"status":200,"message":"Success",...} instead of JSON-RPC 2.0
• The 'S' in "Success" breaks the JSON-RPC parser
• Azure CLI works fine (authentication is valid)
• Other MCP servers (playwright, context7, etc.) work fine (gateway is valid)
• Only Azure MCP integration is broken

Environment

• Docker Desktop: Latest (December 2025)
• Docker MCP Toolkit: Latest (catalog updated 2025-12-12)
• OS: Windows 11

Expected Response (JSON-RPC 2.0)

{"jsonrpc":"2.0","id":1,"result":{...}}

Actual Response (Azure MCP)

{"status":200,"message":"Success","results":[],"duration":89}

Cross-References

• Also reported to: Azure/azure-mcp, microsoft/mcp

[slimslenderslacks]

We are relying on the official SDK here. Right now this means that we can only expose servers that return valid JSON RPC 2.0 messages. If we detect a broken connection on servers from our catalog, we could potentially track broken server versions in the catalog.