The official MCP reference servers (everything, filesystem, memory, sequential-thinking, fetch, git, time) now target the modern spec and TS SDK v2 and still answer legacy clients. Check upgrade impact before bumping.
Key takeaways · AI-distilled
All seven official MCPThe Model Context Protocol — an open standard that lets any AI assistant plug into any tool or data source without custom integration code.Full definition → reference servers were refactored for the modern-era spec while still answering legacy-era clients; the Python fetch, git and time servers serve the 2026-07-28 era beside 2025-11-25.
The TypeScript servers (everything, filesystem, memory and sequential-thinking) moved to TS SDK v2 at version 2.0.0 and raised their Node floor to 24.
In the Python servers, calling an unknown tool now returns a JSON-RPC -32602 error instead of an isError result, each server advertises prompts and resources capabilities, and they require mcp>=2.3,<3.
The filesystem server now revokes access when a roots update leaves no valid root, applies only the newest roots refresh, and holds tool calls while any refresh is pending.
Known issue: in mcp-server-git, the string "null" passed as base_branch or as a branch filter arrives as no value. The cause is a Python SDK bug, and it affects only a branch literally named null.
Terms in this piece · Glossary
MCP — The Model Context Protocol — an open standard that lets any AI assistant plug into any tool or data source without custom integration code.
