Under the hood
MCP connection telemetry now records the length of a server's instructions and whether they were truncated
What
The tengu_mcp_server_connection_succeeded telemetry event, sent when Claude Code successfully connects to an MCP (Model Context Protocol) server, now includes two new fields: instructionsLength, the character count of the instructions text the server returned, and instructionsTruncated, which is true when that text is longer than 2048 characters.
Why
This lets Claude Code track how often MCP servers send unusually long instructions and whether those instructions get cut off, which can affect how well the server's guidance reaches the model.