What
- Adding an MCP server via config now checks its transport type against a host-only set (
sdk,sse-ide,ws-ide) and throws a clear error explaining that such servers are registered by the host application at runtime and can't be stored in configuration. - When processing an
mcp_set_serversupdate, servers of typesse-ideorws-ideare now routed into the blocked/dropped map alongside already-registered names, instead of falling through to the general allow/block logic.
Why These transport types represent servers that only make sense as live, host-managed connections (such as an IDE's own SSE/WebSocket endpoint), so storing or generally allow/block-listing them as regular config entries doesn't make sense; this change makes that restriction explicit and consistent.
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Added since
A small documentation edit on Log at info level touched a line naming sdk after this was published.
For long-running agentic tasks, the TypeScript and Ruby tool runners support automatic [compaction](https://platform.claude.com/docs/en/build-with-claude/context-editing#client-side-compaction-sdk), which generates summaries when token usa…agents-and-tools/tool-use/tool-runner see the edit
Confirmed since
Anthropic's documentation has since written up sdk, on Error reference.
You tried to switch [output styles](/docs/en/output-styles) with `/output-style <style>` or `/config outputStyle=<style>` in a session whose setting sources exclude `local`. Examples are an [Agent SDK](/docs/en/agent-sdk/typescript) sessio…errors see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up sdk, on Error reference.