Azure's MCP server went stateless on 12 October. Some tool names changed with it.
By Lior AharonovFounder, 7IT Solutions ·
Microsoft released Azure MCP Server 3.0 on 12 October 2026 and announced it on 14 October. It uses the stateless MCP protocol 2026-07-28, so clients on that version must send Mcp-Method and Mcp-Name headers on every POST, while clients on 2025-11-25 keep a negotiated fallback. Tool prefixes moved from resilience_* to resiliency_*, and unknown parameters now produce errors.
Picture an agent allowlist that still says resilience_*. After the upgrade it matches nothing, and the agent quietly loses those tools. A big vendor server is now living on the new revision, so your clients will soon expect it from you too.
If you run an MCP server, test it against a 2026-07-28 client that sends Mcp-Method and Mcp-Name headers. If you rename a tool, ship the old name as an alias for one release and say so in your changelog.
A tool name is an API. Renaming it is a breaking change, even when the code behind it is identical.
Lior Aharonov · my takeSources
- Azure SDK Blog: Azure MCP Server 3.0 stable release devblogs.microsoft.com
Researched with AI tools; every fact is checked against the linked sources.