Under the hood
SDK-managed MCP servers pushed at runtime now face stricter rules on type, names, and how they can be toggled
What
The SDK's dynamic MCP server management, used to add or change MCP (Model Context Protocol, a way to connect external tools) servers at runtime, now enforces new restrictions:
- A server pushed while a session is running must be an http server on that session's own MCP proxy route.
- Certain server names are reserved for first-party servers and can only be set when the session starts, not pushed later.
- Servers can only be turned on or off by replacing the entire server set at once, not by toggling one individually.
- A configuration change to a server that's already running is held and applied on the next re-dispatch, rather than immediately.
Why
These restrictions add guardrails around runtime MCP server management, preventing conflicts with built-in servers and making changes to a running server's configuration more predictable.