Under the hood
MCP tool calls to artifact servers now pass through argument-rewriting and result-observing hooks
What
When Claude Code calls a tool on an MCP server (a way for Claude Code to talk to external tools and data sources), it now runs the call's arguments through an argsForCall step before sending them, and runs the response through an observeResult step afterward. A specific handler for the 'artifact' class of MCP servers uses this to rewrite arguments on management calls, and, for list_artifacts calls, to record telemetry including a count of shared artifacts.
Why
This gives Claude Code a hook point to adjust artifact-related MCP calls and to gather usage data on artifact listings, without changing what the tool call looks like to the server itself.